Patent ID: 8430389

Claim:
A sheet processing apparatus comprising: a sheet stacking portion on which a sheet is stacked; a positioning member against which an end of the sheet conveyed to the sheet stacking portion is abutted for a positioning of the conveyed sheets to be made into a sheet bundle on the sheet stacking portion; a staple processing portion which performs, at a stapling position on the sheet bundle, a stapling process to the sheet bundle stacked on the sheet stacking portion, wherein the positioning member is movable to adjust the stapling position on the sheet bundle; a fold processing portion which, after the stapling process is performed, folds the sheet bundle in two to create a folded sheet bundle having a folded end part between a first surface and a second surface; a conveyance guide member which guides the folded sheet bundle being conveyed from the fold processing portion with the folded end part as a leading end while the first surface of the folded sheet bundle slides against the conveyance guide member; an end part processing portion which performs an end part process to the folded end part of the folded sheet bundle guided by the conveyance guide member; and a controlling portion which controls a movement of the positioning member such that, before the staple processing portion performs the stapling process, the stapling position is moved, by a predetermined distance from a center of the sheet bundle, to an area on the sheet bundle that is remote from the center of the sheet bundle and that will become the second surface by the movement of the positioning member, wherein the second surface is opposite to the first surface which slides against the conveyance guide member.