Patent ID: 7946564

Claim:
A sheet processing apparatus, comprising: a sensor to detect a relatively moved sheet; a size calculation unit configured to calculate a size of the sheet based on a detection result of the sensor; a process position adjustment unit configured to adjust, based on the sheet size calculated by the size calculation unit, a position where a specified process is performed to a bundle of sheets as an object of the specified process; a stacker that holds the bundle of sheets as the object of the specified process and can move substantially parallel to a sheet surface direction at a time when the specified process is performed; an alignment roller that comes 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, the alignment roller configured to come in contact with and separate from the bundle of sheets held by the stacker; an information acquisition unit configured to acquire one of information which is a total number of sheets or a thickness of the bundle of sheets detected by the sensor or acquired from an image forming apparatus; and a drive control unit configured to cause the alignment roller to come in contact with the bundle of sheets held by the stacker if the total number of sheets or the thickness of the bundle of sheets is a specified number or more.