Patent ID: 8794617

Claim:
A sheet stacking apparatus configured to perform an alignment process of a sheet conveyed from an image forming apparatus, the sheet stacking apparatus comprising: a discharge portion which discharges a sheet; a stacking portion on which the sheet discharged from the discharge portion is stacked; an abutment portion against which an upstream end in a discharge direction of the sheet discharged on the stacking portion is abutted; a transport member, provided above the discharge portion, which moves to a first position where the transport member is on standby, a second position where the transport member transports the sheet discharged on the stacking portion to abut against the abutment portion so as to perform the alignment process, and a third position where the transport member retracts in the apparatus body; a moving portion which moves the transport member; and a control portion which controls the moving portion so that the transport member is on standby at the first position at the start of an image forming job, the transport member moves between the first position and the second position for each discharge of the sheet by the discharge portion, and the transport member moves to the third position after termination of the alignment processing for a last sheet of the image forming job.