Defense R&D is an essential investment for the national security. Recently our nation has also begun to initiate a number of defense R&D projects. As a lot of fund and resources are allocated to these projects, we need to identify which projects to initiate and then how to manage these projects well. Though there have been a number of studies on R&D projects in commercial sector, there are only a few studies in defense R&D sector. Moreover, these existing defense R&D studies mainly deal with the former issues, which are occurring at the stage of project planing. We are more concerned with project management issues, such as how to manage projects that had already been evaluated to undertake at the planning stage. Specifically our study aims to identify project management factors leading to the success of defense R&D projects. Results of the empirical analysis indicate that management support, user-driven requirements management, and project planning capability are key elements for project performance.