<p>When the clamping force applied from a wrench body (2) on a bolt (100) reaches a prescribed value, a toggle mechanism (4) is actuated. The wrench body (2) tilts with respect to the head member (3) around a connecting shaft (13) as the center. The engagement of a drive pin (11) with a drive pin insertion hole (43) rotates a link arm (40) from an initial position to an operating position. The front surface of a driving-side magnet (45) faces the back surface of a driven-side magnet (9) from behind. Since the back surface of the driven-side magnet (9) and the front surface of the driving-side magnet (45) are of the same pole, a repelling force is generated between the two. The stamp part (6a) of a marking member (19) advances to a forward position that contacts the bolt (100) in opposition to the impelling force of a stamp push-back spring (12), and makes a mark.</p>
