According the Police Weapon Usage Act, Police is allowed to use gun only by meeting the requirement of Article four and five Objectively, Both Articles stipulate the timing and requirement of using police handgun. Therefore, the range of application is much more related to the definition of those two articles. Although police is allowed to use gun by law, the exact timing and degree is not clearly defined. Police on the scene should obey the Article six of "Proportional Alternative rule" It is really difficult to decide case by case. This paper is trying to explain the requirement of using police handgun, and provide some amending suggestions by comparing with related law in Japan.