Known as an essential presence supporting corporate IT development, “SIers (System Integrators)” are increasingly in the spotlight against a backdrop of accelerating DX promotion and cloud adoption.
At the same time, many people still ask: “What exactly does a SIer do?” or “There are so many types — I can’t tell them apart.”
This article provides a comprehensive explanation of SIers — from their basic definition and business processes to the skills required and salary levels. Whether you’re aiming to enter the SIer industry or considering it as a career change option, this guide is for you.
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What Is a SIer?
A SIer (System Integrator) is a specialized firm that supports corporate IT utilization by handling the design, development, and operation of information systems. SIers provide end-to-end services — from building the systems needed to achieve business efficiency and DX (Digital Transformation) to their ongoing maintenance and operation.
Delivering the results clients need requires not only technical expertise but also business understanding and project management capabilities. SIers serve not merely as development vendors, but as IT partners that drive business success.
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Differences Between SIers and Easily Confused Terms
When researching SIers, you frequently come across terms like “SE” and “SES.” These are often confused because they look similar, but their meanings and roles differ significantly. Here we explain the differences between each.
Difference Between SE (Systems Engineer) and SIer
The key distinction between a SIer and an SE is whether it refers to a “company” or an “individual.”
A SIer is a “company” that takes on end-to-end responsibility for system development and operation, whereas an SE refers to a “person” or “job role” that handles the hands-on work of system development. In other words, the engineers working within a SIer company are the SEs.
Furthermore, while SIers are classified by their origin and background, SEs are categorized by their area of specialization. For example, engineers who specialize in network construction are called network engineers, and those who work with cloud environments are called cloud engineers.
Difference Between SES and SIer
SES (System Engineering Service) refers to a service model — or a company providing that service — in which engineers’ labor is supplied to client companies.
The most significant difference between SIers and SES lies in the contract type and the conditions under which payment is made.
SIers typically enter into “contracts for work (請負契約)” and receive payment upon completing a system as a deliverable. SES, on the other hand, enters into “quasi-mandate contracts (準委任契約)”, where payment is made for the engineer’s working hours or labor itself.
Therefore, SES is not fundamentally responsible for delivery. Additionally, while SIers often receive work directly from the client, SES commonly participates in a supporting role within SIer-led projects.
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Main Business Activities and Processes Involved in SIer Work
SIer operations span a wide range of activities, from the initial stages of a project through to operation and maintenance. The skills required and depth of involvement differ at each phase, so understanding each role is essential. Here we explain the representative business activities and processes of a SIer.
1. System Implementation Planning and Requirements Definition
In the initial stage of a project, existing business challenges and requirements are identified, and based on these, the direction for system implementation is clarified.
Specifically, this involves repeated dialogue with the client to create a “requirements definition document” that puts the necessary features and specifications in writing.
The accuracy of alignment and documentation in the early stage is a critical key to project success. If requirements are left ambiguous, it can lead to rework and problems in subsequent phases.
2. The End-to-End Flow from Design Through Development and Implementation
Once requirements are finalized, the project moves into the system design phase. High-level design covers the overall system structure and screen design, while detailed design defines the database and processing logic, after which the project transitions to programming and testing.
Each phase is often divided among team members, making progress and quality management critical. Projects proceed with the goal of balancing quality and deadlines, while also responding flexibly to mid-development specification changes and additional requests.
3. Post-Delivery Operation, Maintenance, and Client Support
In the post-delivery phase, tasks such as monitoring, incident response, and updates are carried out to ensure the built system continues to operate stably. Especially for core business systems, response speed during incidents is directly tied to building trust.
There will also be cases where feature additions or modifications are needed due to regulatory changes or business improvements. SIers that can build long-term support relationships while adapting to client changes are highly valued.
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SIer Classifications and Characteristics by Type
SIers are classified into multiple types based on their origins and capital relationships. Each has different areas of expertise and approaches to business, and understanding these characteristics reveals the structure of the industry.
1. Manufacturer-affiliated SIers
Manufacturer-affiliated SIers often have parent companies in manufacturing or electronics, and excel at providing solutions tied to their own products. Hitachi and Fujitsu are representative examples, characterized by high stability and financial strength.
However, in some cases, their projects are primarily focused on their own group companies, which can limit expansion into other fields.
2. User-affiliated SIers
User-affiliated SIers often originated as the IT departments of large corporations that were spun off as independent entities, and they excel at development based on the business know-how of their parent companies. NTT Data and Nomura Research Institute (NRI), for example, fall into this category.
Because they have a deep understanding of actual business processes, they are capable of making proposals focused on operational efficiency and optimization. While they tend to rely on transactions with their parent company, they have a strength in system proposals from a customer-first perspective.
3. Independent SIers
Independent SIers are companies with no parent company that conduct system development from a neutral standpoint toward their clients. OBIC and Internet Initiative Japan (IIJ) are representative examples, and they are characterized by their involvement in a wide range of projects across industries and sectors.
Because they are not tied to a specific parent company, they can make highly flexible proposals and adopt diverse technologies. On the other hand, they may be at a disadvantage compared to large firms in terms of financial resources, requiring careful risk management when bidding on large-scale projects.
4. Foreign-affiliated SIers
Foreign-affiliated SIers are operated by overseas IT companies that have established Japanese subsidiaries, with Oracle Japan being a prime example. They are based on globally standard technologies and processes, and have particular strength in implementing packages such as ERP systems.
English-language documentation and meetings may be required, making it an attractive environment for globally-minded engineers. However, the results-driven, no-frills culture typical of foreign firms may not suit everyone.
5. Consulting-type SIers
Consulting-type SIers are a model in which strategic or operational consulting firms also handle system development, enabling comprehensive business improvement proposals. They are expected to connect IT with management, and are characterized by their ability to address clients’ fundamental challenges.
They have strength in upstream project phases, providing broad-based support from requirements definition through business reform. However, development phases are often outsourced, and some firms may lack in-house technical capabilities.
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What Are the Benefits of Working at a SIer?
Working at a SIer offers touchpoints with diverse industries and opportunities for skill development, but also has distinctive characteristics in terms of work style and growth environment. Here we introduce three key benefits of working as a SIer professional.
1. High Compensation and a Stable Employment Environment
SIers belonging to large companies or group firms offer a very stable compensation package. Especially at manufacturer-affiliated and user-affiliated firms, long-term career development is facilitated, and there is a tendency for well-established benefits packages and seniority-based salary increase systems.
Furthermore, because many firms handle government agency and infrastructure contracts that are less susceptible to economic fluctuations, there are a notable number of companies whose performance remains stable even during recessions. This kind of environment provides great peace of mind for those who want to work while planning for the future.
2. Gaining Versatile Technical and Management Skills
Since work at SIers is project-based, not only technical skills but also management capabilities such as schedule management and coordination with stakeholders naturally develop over time. Management skills are particularly required at mid-level and above positions.
There are also many opportunities to encounter various business processes and system configurations, creating an environment where versatile knowledge is easily accumulated. These skills and knowledge are all factors valued in the job market, which also broadens your career options.
3. Broad Experience Gained Through Exposure to Various Industries
SIer clients span a wide range of sectors including finance, manufacturing, healthcare, and distribution. As a result, you gain exposure to industry-specific business knowledge and system configurations, cultivating a broad perspective.
Experiencing projects that span multiple industries also nurtures a flexible adaptability that is not dependent on any specific sector — another major benefit.
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Let’s Also Look at the Challenges and Drawbacks of SIers
While SIers have advantages such as stability and broad skill sets, several structural challenges also exist. Here we summarize three representative pain points commonly felt in the field.
1. Difficulty Keeping Up with the Latest Technologies
SIers often handle large-scale projects for major corporations and government agencies, causing development cycles to stretch over long periods. As a result, there is a risk that technology considered cutting-edge at the requirements definition stage may already be outdated by the time of delivery. This characteristic can limit opportunities to take on new technological challenges.
In addition, much of the development is based on existing legacy systems, and there may be few opportunities to practice the latest trends such as cloud-native architectures or agile development. For those who aspire to grow as technologists, this could feel unsatisfying.
Therefore, it is essential to continuously study technology independently and to engage in outside study groups or pursue certifications. Relying solely on workplace projects can easily narrow career breadth, making it important to proactively build one’s own learning environment.
2. The Multi-Layer Subcontracting Structure and Its Workplace Challenges
In the SIer industry, a deeply entrenched multi-layer subcontracting structure exists, where work is broken down from the prime contractor to sub-contractors and even further down the chain. This structure creates a distance between the engineers who do the actual work and the end client, making miscommunication and over-reliance on individual knowledge more likely.
Furthermore, the further down the subcontracting chain, the weaker the bargaining power, which can lead to lower unit prices and excessive headcount management. Working in a system where value is placed on hours rather than outcomes can make it difficult to feel a sense of purpose or growth.
This kind of structure also affects workplace conditions and motivation. Amid ongoing work-style reforms, the SIer industry as a whole is under pressure to reexamine its organizational structures and shift toward outcome-based evaluation systems.
3. The Difficulty of Having Little Control Over Your Own Work
SIers fundamentally work in a position of responding to client requests, which can make it difficult to take the lead in a project. Many decisions — such as specification changes and deadline adjustments — are also made at the client’s discretion, constantly requiring flexible adaptability.
Furthermore, since the client ultimately holds the right to evaluate the final deliverable, it can be difficult to push forward improvement proposals according to your own firm’s policies. In such an environment, the autonomy to drive a project forward on your own terms is limited, and there are often moments of frustration.
On the flip side, what is expected is “the ability to understand client needs and respond accurately.” By collaborating with leaders and sales teams and steadily building client trust, you can gradually earn a greater voice and more opportunities to make proposals.
The Current State and Future Outlook of the SIer Industry
The SIer industry faces a combination of stability through large-scale projects and rapid technological innovation alongside shifts in business models. Here we examine the position and challenges of SIers in a changing era.
1. Changing Roles for SIers in the DX Era
In recent years, the wave of Digital Transformation (DX) has spread rapidly, and SIers are also being called upon to change. The attitude of actively engaging in client business transformation, rather than simply “building what you’re told,” is increasingly valued.
Because DX delves deeply into non-IT domains such as business reform and improving customer experience, SIers also need a consulting-oriented perspective. The presence or absence of skills in business understanding and strategic proposals — on top of existing development capabilities — is becoming a key competitive differentiator.
To adapt to changing required skills and mindsets, re-educating employees and leveraging external talent are indispensable. The industry as a whole is also being pushed to transform beyond its traditional framework, with an organizational structure that can flexibly adopt cutting-edge technologies such as cloud, AI, and IoT.
2. The Talent Shortage and the Challenges Behind It
The SIer industry faces a chronic talent shortage, with securing engineers and project managers for development roles being a particular challenge. The aging of the technical workforce and declining interest in IT among younger generations have also contributed, and competition for talent grows fiercer every year.
Contributing factors include a tendency for long working hours and the irregular working patterns tied to project cycles to deter potential candidates. Furthermore, the nature of contract-based development makes it difficult for technical innovation to advance within companies, which is also a factor making talent retention challenging.
In response to these challenges, work-style reforms are being pursued, including strengthening training programs and introducing flexible work-hour systems.
An increasing number of companies are also diversifying their recruitment channels, such as hiring in regional areas and utilizing foreign engineers.
3 Characteristics of People Well-Suited for SIer Work
Working at a SIer requires not just technical skills, but also the mindset and behavioral traits needed to perform the job effectively. Here we introduce three types of people who are likely to thrive in the field.
1. People Who Approach Tasks with Planning and Logic
SIer work requires long-term schedule management and the methodical execution of plans at each phase. Coordinating with many stakeholders, visualizing progress, detecting early signs of delays, and implementing countermeasures are all essential. In such situations, the ability to process tasks in a planned, organized manner is a major asset.
When explaining things to clients or communicating within the team, the skill to organize and convey information logically is also important. Structurally grasping problems and building consensus — while drawing on a technical background — leads to project success.
2. Communication-Oriented People Who Don’t Mind Coordinating Inside and Outside the Organization
At a SIer, you need to work closely with people in diverse roles — clients, developers, and sales staff. Understanding each party’s interests and position, and then exercising the coordination skills to move things forward smoothly, is extremely important in the field.
In particular, accurately grasping the client’s intent and correctly relaying it to the technical team is a required role, especially during the requirements definition and delivery phases. The ability to read between the lines in conversation and reflect that understanding appropriately is the key to smooth SIer operations.
3. People Who Want to Balance Stability with Growth
SIers include many group companies of large corporations, making stability of employment and comprehensive benefits packages an attractive draw. For those who value a steady work style, conditions are well-established for building a long-term career.
At the same time, since you are involved in a wide range of industries and projects, there is ample room to grow by acquiring new skills. For those who value a balance between stability and challenge, a SIer is an ideal workplace.
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What Skills and Certifications Are Needed for SIer Work?
Excelling as a SIer requires a broad range of skills — not just IT knowledge, but also management and interpersonal capabilities. Here we introduce the critical skills directly relevant to the work and the certifications worth obtaining.
1. Project Management Skills to Drive Projects Forward
Because SIer work consists of multiple phases and team members, the skill to oversee the entire project and develop plans is indispensable. Sound judgment in phase management, resource allocation, and risk response all underpin smooth project execution.
Especially at the leader level, there are many situations involving coordination with clients and quality assurance of deliverables, and the difference in management capability can determine a project’s success or failure. While this is a skill that develops gradually through hands-on experience, having foundational management knowledge is also effective.
2. Analytical Thinking to Logically Organize Problems
The ability to structurally break down and organize complex requirements and vague requests is essential. The skill of visualizing business flows and the root cause of problems, and guiding toward the optimal solution, is directly linked to improved project quality.
This capability proves its worth during client presentations as well as when responding to issues that arise during development. A mindset of thinking things through logically also builds trust within and outside the team, raising your value as a technical professional.
3. Foundational IT Skills for Design, Development, and Maintenance
For system design and development, a broad range of fundamental IT knowledge is required, including programming languages, databases, networking, and security. A deep technical understanding is especially indispensable when involved in requirements definition and design phases.
In the maintenance phase, capabilities in troubleshooting and performance improvement from an operational perspective are also necessary. Because SIer professionals are in a position to be involved in all phases, mastering a broad base of fundamentals — rather than fragmented knowledge — becomes a strength.
4. Certifications That Are Useful in Practice
As you build a career as a SIer, certifications serve as proof of your practical capabilities and are directly tied to earning trust from clients and colleagues alike. In particular, certifications related to specialized fields such as project management, infrastructure, and development are closely linked to day-to-day work and become a major asset.
Representative national certifications include the “Fundamental Information Technology Engineer Examination” and the “Applied Information Technology Engineer Examination.” These cover the fundamental knowledge and skills required of an IT engineer and are useful across all SIer business activities.
Furthermore, “PMP (Project Management Professional)”, an international project management certification, is ideal for those aiming to step up into a managerial role, and tends to be highly regarded in foreign-affiliated firms and large-scale projects.
In the cloud and infrastructure domain, vendor certifications such as AWS certifications and Microsoft Azure certifications are extremely valuable. As they demonstrate knowledge in designing and operating cloud implementation projects, they are also well-regarded in DX-related projects and sales proposals.
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Representative SIers by Type and Their Average Annual Salaries
Finally, here is the average annual salary for major SIers across manufacturer-affiliated, user-affiliated, independent, and foreign-affiliated categories.
1. Hitachi, Ltd. (Manufacturer-affiliated): Average Annual Salary ¥9.35 million
Hitachi, Ltd. is a comprehensive enterprise group that, in addition to its track record in the electrical equipment and social infrastructure sectors, has also strengthened its IT and system development operations. It is a prime example of a manufacturer-affiliated SIer that deploys large-scale projects in coordination with its own products.
The FY2023 Securities Report states an average annual salary of ¥9,359,857.
Centered on social infrastructure IT systems such as energy and railways, it offers high stability and social contribution, and is also a SIer committed to the SDGs.
2. Fujitsu (Manufacturer-affiliated): Average Annual Salary ¥9.29 million
Fujitsu is a comprehensive manufacturer-affiliated SIer providing IT solutions both domestically and internationally, with a strong focus on DX, cloud, and security. Its strengths include not only technical capabilities but also a high capacity to handle global projects.
The FY2024 Securities Report records an average annual salary of ¥9,291,084.
3. Nomura Research Institute (User-affiliated): Average Annual Salary ¥13.22 million
Nomura Research Institute (NRI) is a user-affiliated SIer with strengths in the finance and distribution sectors, providing solutions that integrate consulting and IT services. It is characterized by a high volume of projects that deeply involve clients’ business transformation, and involvement from upstream phases requires a high level of specialized knowledge.
The FY2025 Securities Report states an average employee annual salary of ¥13,217,000. This salary level is top-class among domestic SIers.
A deeply rooted culture where results and responsibilities are comprehensively evaluated also translates into performance-oriented compensation.
4. NTT Data (User-affiliated): Average Annual Salary ¥9.23 million
NTT Data is Japan’s largest class of user-affiliated SIer, with strengths in large-scale projects in finance, construction, and healthcare. A major characteristic is its ability to leverage group resources to respond to a wide range of business domains using data-driven approaches.
The FY2025 Securities Report reports an average salary of ¥9,234,000.
Global expansion and the diversity of career paths are also attractive, with systems in place to accommodate both technically-oriented and management-oriented career tracks. An evaluation framework based on industry standards is also a characteristic feature.
Furthermore, training programs and career support are well-developed, with a well-designed system tailored to individual growth ambitions. Field autonomy is considerable, and a culture exists that actively supports engineers’ skill development.
5. OBIC (Independent): Average Annual Salary ¥11.03 million
OBIC is an independent SIer that operates in a fully integrated model, handling the development and sales of business package software alongside consulting and implementation support. The tight integration between consulting, development, and support in a one-stop solution service is what generates its efficiency.
The FY2025 Securities Report reports an average annual salary of ¥11,031,000.
Centered on “OBIC7,” its integrated business software by industry and function, the company supports clients in improving operational efficiency and management performance. It provides services that respond closely to the individual needs of each company, building a solid reputation and track record.
6. Oracle Japan (Foreign-affiliated): Average Annual Salary ¥11.61 million
Oracle Japan is a foreign-affiliated SIer with ERP and database expertise and a global customer base.
The FY2024 Securities Report discloses an average annual salary of ¥11,609,152.
The company actively supports employee social contribution activities, with a deeply embedded culture in which employees participate in volunteer activities around the world. It is also characterized by dedicated efforts to fulfill corporate social responsibility, including educational support and contributions to local communities.
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Summary
SIers play a diverse range of roles on the front lines of Japanese corporate IT strategy — from design and development through to operation. While characteristics vary by type and size, what they all have in common is the mission of “solving client challenges through technology.”
At the same time, structural challenges and the difficulty of keeping pace with technological change also exist. That is precisely why the self-driven initiative to grow without relying on one’s environment is so important.
By combining business skills such as planning ability, communication skills, and logical thinking, working as a SIer offers the appeal of achieving both stability and growth simultaneously.
SIers will continue to be an indispensable presence as a bridge between IT and management going forward. Those who can flexibly adapt to evolving technologies and markets will be the ones who carry SIers at their core into the future.
