Provided is a sheet processing apparatus including a gripper unit which is moved to a retreat region along long grooves in advance when moving a stapler unit to any one of first and second binding positions. The stapler unit is moved to the binding position by being guided by a guide rail portion while passing above the long grooves. Therefore, moving operations of both of the gripper unit and the stapler unit can be smoothly performed under a state in which movement of both thereof is not prohibited by the long grooves and the guide rail portion. Further, an image forming apparatus including the sheet processing apparatus is provided.