Patent ID: 7747212

Claim:
A sheet processing apparatus that applies post-processing to sheets conveyed from an image forming apparatus, comprising: a post-processing unit for applying the post-processing to the sheets conveyed from the image forming apparatus; a first aligning unit configured to convey the sheets in a first direction toward the post-processing unit and bring an edge of the sheets into contact with a movable stopper, which is arranged in a conveying path for the sheets, to align the sheets in a conveying direction; a second aligning unit configured to hold the sheets with a pair of movable aligning plates from both sides along the first direction to align the sheets in a direction orthogonal to the conveying direction; and a control unit configured to discriminate a size of the sheets on the basis of input information from an operation unit provided in the image forming apparatus and switch a position of the stopper according to the size of the sheets discriminated, and control the pair of aligning plates to be located on both sides close to a center of the sheets when the sheets are brought into contact with the stopper, wherein the post-processing unit applies the post-processing to the sheets aligned.