Risk management activity for successful defense R&D project should be done anticipatorily and consistently over the entire project period and there should be a priority for management depending on importance of the risk factors. In this study, we verified the reliability and validity through factor analysis for the risk factors selected by the Delphi technique. We also obtained the relative importance of risk factors with analytic hierarchy process (AHP) and decided to prioritize for comparison of domestic and overseas research. According to the study, we found that it is important to settle the requirements and to classify the scope of R&D. It is also considered significant to have reasonable schedule for completion and secure the necessary resources in the early stage of project. Unlike previous studies, it appeared the technical factors are critical elements as well for defense R&D project.