A sheet processing apparatus is provided with a sheet discharge path (first carry-in path P1) that sequentially carries out a sheet, a processing tray that collects sheets from the sheet discharge path in the shape of a bunch, a stacker that holds the sheets from the processing tray, and bunch carrying device disposed in the processing tray to carry out a bunch of sheets toward the stacker. The bunch carrying-out device includes a carrier member disposed movably in the sheet-bunch carrying-out direction of the processing tray, and a sheet engagement member that engages the bunch of sheets on the processing tray. The sheet engagement member is mounted on the carrier member to be able to move to position in the sheet-bunch carrying-out direction.