Abstract: A stapler comprising a striking block having a staple striking blade for striking staples on its end; a motor for causing reciprocating motion of the staple striking block over a range from the staple striking position to a stopping position apart from the staple; a switch that is provided at the location of movement of the striking block, and is turned on and off by the motion of the striking block; and a control circuit which reverses the driving direction of the driving means, moves the striking block to the stopping position, and turns off the switching means, in case the switching means is not turned off within a predetermined time after the switching means is turned on by the motion of the striking block.