A rotary shaft is provided in association with a distal end face in a transport direction of a sheet held on a waiting tray, the sheet being retained in a waiting mode. Then, a distal end lower end support member and a paddle member are mounted coaxially, and the rotary shaft is rotated. In this manner, standby retention, retention release, and alignment processes are carried out in order. During retention in a waiting mode, the distal end lower face support member supports a sheet distal end lower face. During release of the retention, this support member releases the support of the sheet distal end lower face. During the sheet alignment process, the alignment paddle member carries out alignment processing of the distal end in the transport direction of the sheet dropped onto a processing tray.