At one end of a stacking area (12), stack abutments (14) are arranged which extend into, and can be moved out of the feeding path (13) of sheets fed into said area. In the area of the stack abutments (14), two oppositely arranged stapling devices (15) are located which are movable parallely with the stack side defined by the stack abutments (14) and are adjustable to various stapling distances. The stapling devices (15) engage a spindle (17) with oppositely directed threads (18) such that when the spindle (17) is rotated the stapling devices (15) are moved towards, or away from each other. The stapling devices (15) each laterally surround the stacking area (12). For this purpose they are provided with recesses (24) through which the sheets can be brought into the stapling position on the stack abutments (14) and the stapled stacks can be removed respectively.