Patent ID: 8899579

Claim:
A sheet processing apparatus comprising: a sheet processing portion configured to process a sheet bundle; a sheet stacking portion configured to stack thereon the sheet bundle discharged from a discharge port after being processed on the sheet processing portion; a regulating portion disposed below the discharge port and configured to regulate a position of an upstream edge, in a discharging direction of the sheet bundle discharged to the sheet stacking portion; a sheet supporting portion configured to support the sheet bundle; a moving portion configured to move the sheet supporting portion to a first position where the sheet supporting portion projects above the sheet stacking portion to support an upstream edge portion of the sheet bundle discharged from the discharge port, a second position where the sheet supporting portion releases supporting the upstream edge portion of the sheet bundle to stack the discharged sheet bundle on a sheet bundle previously stacked on the sheet stacking portion, and a stacking position where the sheet supporting portion supports a sheet bundle being processed by the sheet processing portion, the stacking position being above the first position; and a control portion configured to control the moving portion so that, after a sheet bundle is processed by the sheet processing portion, the sheet supporting portion is moved from the stacking position to the first position to support the upstream edge portion of the sheet bundle discharged from the discharge port, and sheet supporting portion is moved from the first position to the second position while the upstream edge portion of the sheet bundle is on the sheet supporting portion so as to pull the upstream edge of the sheet bundle to contact with the regulating portion.