A stapler comprises a stapling unit and a base movably connected to each other. The base comprises an anvil, a lower and an upper part with a contact surface which has a staple opening against which a workpiece is placed. The upper and lower parts are movably connected to each other. In operation, movement of the stapling unit and the base toward each other drives a staple into the workpiece, wherein the staple crown comes in contact with the workpiece and the staple legs extend through the staple opening. Upon movement of the upper part and stapling unit toward the lower part, the staple legs are bent by the anvil into contact with the underside of the workpiece. The anvil is attached to the base by an elastic element between the lower and upper part, and is urged toward the staple opening to block the opening when the stapler is in an initial position.