To bind a bunch of sheets by using a small device in a simple structure.

A discharge roller 20 discharges sheets. A shutter 13 stops and positions the sheets in place. A stapler 14 binds the positioned sheets. A discharge roller 12 is located under the discharge roller 20 for abutting the sheets to the shutter 13, aligning the sheets and discharging sheets after bound. A changing flapper 15 changer the passage of the sheets to be carried to either the discharge roller 20 or the discharge roller 12.