A sheet processing apparatus includes: a conveying unit configured to convey a sheet along a sheet conveyance path; a conveyance-path supporting unit configured to support both ends of the sheet conveyance path with respect to a direction perpendicular to a sheet conveying direction; a first stitching unit configured to stitch the sheets conveyed; a second stitching unit configured to stitch the sheets conveyed; a first moving unit configured to move the first stitching unit in a direction perpendicular to the sheet conveying direction; and a second moving unit configured to move the second stitching unit in a direction perpendicular to the sheet conveying direction, wherein any one of the first stitching unit and the second stitching unit is movable to outside of the conveyance-path supporting unit.