A staple gun includes a housing, a striking member, a driving mechanism and a locking mechanism. The housing includes a staple outlet. The striking member is disposed on the housing. The driving mechanism includes a pressure bar which is rotatably assembled with the housing. The locking mechanism includes a locking member. The locking member is assembled with the housing and is rotatable about an axial direction to be in a locking position or a releasing position. The locking member has a stopping bump formed radially.