Patent ID: 7654511

Claim:
A sheet post-processing apparatus comprising: a mount section to mount sheets ejected from an image formation section; an aligning section that aligns side-end portions of a sheet ejected on the mount section and moves a bundle of the sheets to post-processing undergoing positions and wherein the aligning section determines whether or not to move the sheets corresponding to a size of the sheets; a post-processing section that performs binding processing on the bundle of the sheets, aligned by the aligning section, mounted on the mount section, wherein the post- processing undergoing positions are substantially parallel to a travel direction of the post-processing section; a moving section that moves the post-processing section to a plurality of post-processing positions set corresponding to a size of the sheets to perform the binding processing at different binding processing target positions on the bundle of the sheets; and a control unit that operates to cause the moving section to move the post-processing section during the binding processing in a direction opposite to any of the directions in which the control unit operates the aligning section to move the bundle of sheets to the plurality of post-processing positions; wherein the post-processing section has a single stapler which performs the binding processing on the bundle of sheets.