A slide frame is mounted on a driver unit that can be vertically reversed on a base frame. A guide pin disposed in the slide frame engages with a concave portion of a cam plate portion formed in the base frame. When a fixation releasing handle of the driver unit is operated, a lever pushes the slide frame to slide the slide frame and the guide pin is deviated from the concave portion to rotate the driver unit. In a state where the driver unit is fixed in a regular posture, since the guide pin is pushing a switch lever, the detection switch is kept turned ON and thus an electric stapler is in an operable state. When the driver unit is rotated, the switch lever is released from the press of the guide pin and the detection switch is turned OFF, thereby cutting off the power.