In general, researchers, policymakers, and practitioners consider innovation by producers as a primary mode in a market economy. However, the recent research has shown that some of the most important, novel products and processes have been developed by users-both user firms and individual end-users. According to von Hippel [1988], he found that they were the developers who made about 80 percent of the most important scientific instrument innovations as well as the major innovations in semiconductor processing. In this research, we conducted grounded research on user-led innovation at the corporate-level. Also, we analyzed the train development project (SR000) of Seoul Metropolitan Rapid Transit Corporation (SMRT). We focused on identifying the success factors of user-led innovation, and development process.