A sheet processing apparatus includes a conveying portion, a first stack portion on which sheets conveyed are stacked, a first regulating portion which regulates a position of a sheet bundle in a crossing direction crossing to the sheet transport direction, a second regulating portion which regulates a position of a sheet bundle in the conveying direction, a first binding portion binding a corner portion of the sheet bundle by a staple, a second binding portion which binds a corner portion of a sheet bundle without a staple, a second stack portion which stacks a sheet bundle discharged from the first stack portion, and a lifting-lowering motor which lifts and lowers the second stack portion. The lifting-lowering motor is located at a downstream, in the conveying direction, of a first binding position where the first binding portion binds a sheet bundle.

The purpose of the present invention is to provide a post-processing apparatus capable of performing conveying to and storing at a predetermined stack tray without causing sheet jamming even when a sheet having larger size than a standard size is introduced. The present invention comprises a post-processing apparatus as a processing tray on which sheets conveyed in a predetermined conveyance direction are stacked into a bundle shape, an aligning device which aligns the sheets conveyed to the processing tray, a binding device which performs a binding process on the sheets aligned by the aligning device, and a controller which controls the aligning device so that a sheet is aligned at a position being apart from the binding device by a predetermined distance when the sheet conveyed to the processing tray has a predetermined size or larger.