Patent ID: 8459629

Claim:
A sheet processing apparatus comprising: a conveying portion which is contactable with and separable from a surface of a doubled up booklet and conveys the booklet; an end conveying portion which abuts against an open end of the booklet and pushes out the booklet, thereby conveying the booklet; a stopper which abuts against a back of the booklet to position the booklet; a holding portion which holds the booklet which abuts against the stopper; a processing portion which processes the booklet held by the holding portion; a changing portion which changes a pressure of the conveying portion against the surface of the booklet while the conveying portion contacts the surface of the booklet; and a controlling portion configured to control the changing portion, the end conveying portion, and the holding portion so that the changing portion reduces the pressure of the conveying portion against the surface of the booklet before the back of the booklet conveyed by the conveying portion abuts against the stopper, while the booklet is conveyed by the end conveying portion until the back of the booklet abuts against the stopper and then, the holding portion holds the booklet.