There are provided a sheet inlet, a saddle-stitch compilation tray for aligning and accommodating plural sheets that are input through the sheet inlet, and a rotary cutter unit for cutting a saddle-stitched sheaf of sheets accommodated in the saddle-stitch compilation tray. In the rotary cutter unit, a sheaf of sheets is cut by moving a circular blade in a direction perpendicular to a sheet transport direction of a sheet transport path from one end in the direction perpendicular to the sheet transport direction. Different sheaves of sheets may be cut by a go-movement and a return-movement of the circular blade.