Patent ID: 7832715

Claim:
A sheet processing apparatus comprising: a stacker that holds a sheet bundle and can move substantially in parallel to a sheet surface of the sheet bundle; an alignment roller that can come in contact with and be separated from a sheet surface of a sheet held by the stacker and causes the sheet to be abutted against a reference position in the stacker and to be aligned by bringing a rotating roller surface into contact with the sheet; a stapler to perform a stapling process on the sheet bundle which is aligned by the alignment roller and is moved to a specified position by the stacker; a control unit configured to bring the rotating alignment roller into contact with the sheet bundle held by the stacker when the sheet bundle on which the stapling process is performed is moved by the stacker in a direction retracting from the stapler; and an information acquisition unit configured to acquire information relating to a thickness of the sheet constituting the sheet bundle, when the sheet bundle on which the stapling process is performed is moved by the stacker in the direction retracting from the stapler, as the thickness of the sheet becomes thick, the control unit prolongs a time in which the alignment roller is in contact with the sheet bundle held by the stacker.