PURPOSE: To provide a stapler, with which no unavailing action is present after the installation of a cartridge and the striking-in of a staple is realized since the first striking-in action after the installation of the cartridge.

CONSTITUTION: When a residual amount detecting means 5 detects null needle and then a clinching position detecting means 4 detects a clinching position, a one-cycle action driving motor 51 is stopped by a driving controlling part 8. By actuating the driving motor 51 after the change of cartridges, the stapling operation is re-started from the process returning from the clanching position to the home position or from the feeding action of stapler performing during the returning process.