The present invention provides a sheet processing apparatus and an image forming apparatus in which even if the apparatus includes a gripping apparatus gripping one side of a sheet bundle to be stapled, the sheet bundle can be stapled in a portion thereof in which the gripping apparatus is located. A gripper unit is moved in a direction crossing one side of sheets and placed in a discharge position in which the gripper unit discharges the gripped sheets and in a coupling position where the gripper unit is coupled to a staple unit. The gripper unit is thus moved in the same direction as that in which the staple unit coupled to the gripper unit at the coupling position moves. Thus, the staple unit can be moved to a stapling position without the need to ensure a retract space.