Patent ID: 8882105

Claim:
A sheet stacking apparatus, comprising: a sheet discharge portion configured to discharge a sheet; a stacking portion on which the sheet discharged by the sheet discharge portion is stacked; a raising/lowering portion configured to raise or lower the stacking portion; a detecting portion configured to detect a topmost sheet which is stacked on the stacking portion; an alignment portion having a pair of alignment members arranged on both sides of the sheet on the stacking portion in a sheet width direction orthogonal to a sheet discharge direction, and the alignment portion performing an alignment operation in which at least one of the pair of alignment members moves to align the topmost sheet on the stacking portion; and a control portion configured to control the raising/lowering portion so that the topmost sheet is at a predetermined height in accordance with a detection result obtained from the detecting portion and configured to control the alignment portion to perform the alignment operation when the sheet is discharged by the sheet discharge portion, wherein the control portion is configured to control the alignment portion so as not to perform the alignment operation when the sheet is discharged by the sheet discharge portion in a case where the control portion determines that a movement amount of the stacking portion, at the time when the stacking portion is moved so that the topmost sheet is at the predetermined height in accordance with the detection result obtained from the detecting portion, exceeds a predetermined movement amount.