<p>A stationary anvil (17) and a movable anvil (19) are formed in a hammer-out section (7). The movable anvil (19) is advanceable into a drive path (18) while facing the stationary anvil (17). A forming/driving mechanism (8) is constituted of a driver plate (9) for driving out a staple in the drive path (18) and a forming plate (10) for simultaneously forming not-yet-formed staple materials placed on the movable anvil (19) in the drive path (18) and on the stationary anvil (17). The not-yet-formed staple materials are formed into a squared C-shape by operating the forming plate (10), and then the driver plate (9) is operated on the same plane as the forming plate (10).</p>
