A rotary shaft is allocated in association with a distal end face in a transport direction of a sheet retained on a waiting tray in a waiting mode. On this rotary shaft, a distal end lower face support member, an upper face slash member, and a sheet alignment paddle member are coaxially mounted. Then, by rotating the rotary shaft, standby retention, support release, and sheet alignment processes are carried out in order with respect to the sheet on the waiting tray.