Weapon system currently considers the research about effect analysis including cost effectiveness methodology for a budget management and an achievement of the military strategy goal. So that, this study considers the theoretical background, strength and weakness of several Multi-Criteria Decision Making, and an effect analysis of weapon system. And AHP(Analytic Hierarchy Process) is selected for the best effect analysis methodology of weapon system. Therefore, we applied AHP to the case study of the new generation Multiple Launcher Rocket System, performing the analysis of cost effectiveness methodology. Using AHP and cost effectiveness methodology, we propose the actual and proper decision making result.