An electric stapler includes: a driver (3) for driving leg portions of a staple having a U-shaped section to penetrate the leg portions through a paper bundle; a table (4) including a clincher (7) for bending and forming the penetrated leg portions inwardly, the table (4) for holding the paper bundle between the driver (3) and the table (4); a motor for moving the table (4) and the driver (3); a photo sensor (10) for detecting an existence of the paper bundle inserted into a gap between the table (4) and the driver (3); and a control portion for driving the motor. The photo sensor (10) is disposed on the table (4) in such a manner that a detection point of the photo sensor (10) for detecting the paper bundle exists upwardly of a disposing position of the clincher (7) by inclining an optical axis direction of a radiation light to be emitted from the photo sensor (10) in a direction of the clincher (7).