A finisher is provided with a transport paddle and a control portion. The transport paddle freely moves to a first position where the transport paddle is on standby while protruding above a lower stack tray, a second position where the transport paddle sandwiches the sheet in between and, at the same time, is transported to abut the sheet against the abutment portion, and a third position where the transport paddle retracts in a finisher body 400. The control portion makes the transport paddle be on standby at the first position at least at the start of a job, moves the transport paddle between the first position and the second position for each discharge of the sheet by the bundle discharge roller pair, and moves the transport paddle to the third position after termination of the alignment processing for a last sheet of the job.