A puncher 10 includes a pair of side members 14, 15 disposed on a base 12 having a support surface 11 for sheets P, an operation lever 18 rotatable around a rotation shaft 16 provided between the side members 14, 15, punch blades 24 supported by a slide member 20 provided movable vertically between the side members, and link members 21 each connecting the operation lever 18 and slide member 20 relatively rotatably. Each of the link members 21 is provided in an arc piece shape being symmetrical with respect to a center thereof, and a connecting position A2 between the link member 21 and the slide member 20 is located substantially on the same axis line as that of the punch blades 24.