The purpose of this study is utilizing hazard analysis to assess the weapon system. The weapons are highly dangerous system. The accident occurred often because the weapon operated improperly. The casualty happened frequently in recent years in military. It is an important factor for lack of crisis management in advance. We all know that “safety is first”. This study is in order to fulfill the policy of “prevention is better than cure” by hazard analysis. In order to bring the function of the weapon system into full play, we should improve the safety for operating weapon system.