Sheet processing apparatus and image forming system

A sheet processing apparatus comprising:

• a stapling unit that staples a sheet member;
• a moving unit on which the stapling unit is mounted via a rotatable first rotating member;
• a driving unit that linearly moves the moving unit;
• a rotatable second rotating member that is disposed in the moving unit, changes an orientation of the stapling unit in cooperation with the first rotating member, and includes an abutting member;
• a holding unit that holds the orientation of the stapling unit at a plurality of positions;
• an abutted member that changes the orientation of the stapling unit held by the holding unit via the second rotating member;
• and
• a restricting member disposed in parallel with a direction in which the stapling unit moves, the restricting member restricting the orientation of the stapling unit held by the holding unit.