Patent ID: 8220790

Claim:
A sheet processing apparatus, comprising: an information acquisition unit configured to acquire a sheet size of a relatively moved sheet; a process position adjustment unit configured to adjust, based on the sheet size acquired by the information acquisition unit, a position where a specified process is performed to a bundle of sheets as an object of the specified process; a stacker configured to hold the bundle of sheets as the object of the specified process and configured to move substantially parallel to a sheet surface direction at a time when the specified process is performed; an alignment member configured to come into contact with the sheet as the sheet is being stacked in the stacker to cause the sheet to be struck against a reference position in the stacker and to be aligned, and come in contact with and separate from the bundle of sheets held by the stacker; and a drive control unit configured to cause the alignment member to come in contact with the bundle of sheets held by the stacker based on the sheet size acquired by the information acquisition unit, and cause, if the sheet size acquired by the information acquisition unit is larger than a predetermined sheet size, the alignment member to come in contact with the bundle of sheets at an earlier timing compared to the timing at which the alignment member is caused to come in contact with the bundle of sheets when the sheet size acquired by the information acquisition unit is not larger than the predetermined sheet size.