Sheet processing apparatus and image forming apparatus comprising same

An image forming apparatus comprising:

• a sheet processing apparatus, wherein the sheet processing apparatus includes
• a first support member that contacts an end portion of a sheet member on an upstream side of a sheet member conveyance direction during alignment of the sheet member,
• a second support member for supporting another part of the sheet member,
• a stapling unit for stapling an inserted sheet member, the stapling unit including a stapler and a lever configured to contact a protrusion, the stapling unit being configured so that lever rotates the stapler as the lever contacts the protrusion,
• a moving mechanism configured to move the stapling unit in an orthogonal direction to a sheet member conveyance direction, and
• a single drive source for driving the moving mechanism, wherein the protrusion is in a preset position during a process of moving the stapling unit using the moving mechanism,
• wherein the protrusion includes a first protrusion for setting the stapling unit in the oblique stapling condition, and a second protrusion for returning the stapling unit to the parallel stapling condition from the oblique stapling condition.