In embedded systems like weapon systems, the proportion of software has been growing and the quality of software, which provides complicated functionalities of a system and controls hardware, affects the quality of the entire system. Besides, to implement/acquire reliable software, we need the efforts for assuring process quality as well as product quality in the whole software development life cycle. In this paper, we propose a framework to assure software reliability of weapon systems in Korean defense domain. The framework provides a guideline for software reliability evaluation to software organizations and pursues the improvement of software engineering process which supports activities and indicators for quantitative project management in the software development process. We also present the empirical study of the application of the proposed framework and the analysis results on the effectiveness of the proposed framework.