To provide a stapler which reduces the load on a driver means for driving the staple in a sheet bundle, smoothes the driving motion of the driver means, and suppresses troubles such as defective binding.

This stapler comprises the staples 200 continuously connected in a strip, a staple feed claw 25 for successively advancing the staples 200 to the staple position 103, the driver means 50 for driving the staple 200 fed to the staple position 103 at an appropriate position of the sheet bundle, and a clincher means 40 for bending the tips of the staples 200 driven and pierced in the sheet bundle. The staples 200 for oscillating the staple feed claw 25 in the bending motion of the clincher means 40 and successively advancing the staples to the staple position 103.