A post-processing apparatus includes a sheet discharge tray to which a sheet or a sheet bundle is discharged, and a shift mechanism configured to shift a discharge position of the sheet or the sheet bundle discharged to the sheet discharge tray from a reference position. The apparatus further includes a controller configured to control the shift mechanism to divide the sheet or the sheet bundle in a first direction in a direction orthogonal to a conveyance direction of the sheet or the sheet bundle and a second direction opposite to the first direction.