Patent ID: 8544834

Claim:
A sheet processing apparatus, comprising: a conveying portion which conveys a folded sheet bundle with a fold end portion in the lead; a sheet holding portion which nips to deform and hold the sheet bundle conveyed and stopped by the conveying portion; a pressing portion which presses a tip of the fold end portion of the sheet bundle held by the sheet holding portion to deform the fold end portion into a square shape; a moving portion which moves the sheet holding portion to or from the pressing portion in a conveying direction while the sheet holding portion holds the sheet bundle; and a controlling portion which controls the moving portion to move the sheet holding portion in the conveying direction so that a distance in the conveying direction between a pressing position where the pressing portion presses the tip of the fold end portion and a tip position of the fold end portion after the sheet holding portion deforms the fold end portion but before the pressing portion deforms the fold end portion, becomes a constant distance.