Sheet stacking apparatus and image forming apparatus

A sheet stacking apparatus comprising:

• a sheet discharging portion configured to discharge a sheet;
• a sheet stacking portion on which the sheet discharged from the sheet discharging portion is stacked;
• an abutting portion against which a sheet edge abuts, and configured to position the sheet stacked on the sheet stacking portion at a predetermined position;
• a shifting unit configured to shift the sheet discharged on the sheet stacking portion to the abutting portion;
• and
• a plurality of pressing members arranged in a shifting direction and upstream of the shifting unit in the shifting direction of the shifting unit, configured to move down to press the sheet stacked on the sheet stacking portion from a retracted position where the pressing member is separated from the sheet stacked on the sheet stacking portion;
• and
• a controller to control the sheet stacking apparatus,
• where the sheet is sequentially pressed by the plurality of pressing members from a near side of the abutting portion to an opposite side,
• wherein after the sheet edge abuts against the abutting portion by a shifting operation of the shifting unit, the sheet is pressed towards a sheet stacking face of the sheet stacking portion by downward movement of the pressing member from the retracted position while the shifting unit applies a continuous force to keep the sheet edge at the abutting portion.