To improve the quality of paper arrangement without lowering productivity.

Cams 53 formed integrally with gears are disposed on both sides of a bundle carrying roller 13a fixed to a staple tray 10 to be rotated around a roller shaft. The cams 53 are rotated by a force transmitted from the gears 52b, and raise sliders 54 disposed on both sides of the bundle carrying roller 13b on a movable side so as to be rotated about the roller shaft to release the bundle carrying roller 13b on the movable side along the inner diameters of bearings 55 on both sides. A lever 60c fixed to a rear end fence drive shaft 60a is rotated by the rotation of the cams 53, the operation of a lever 63c fixed to one side of the rotating shaft 63a is transmitted to a rear end fence 27 through a bearing 61 and a link 62 to project or retreat the rear end fence 27 in a paper abutting direction.