A sheet processing apparatus includes a transport path to transport a sheet to a first tray, a branch path branched off from the transport path to transport a sheet to a second tray, a first transport roller positioned in the transport path on a downstream side of a branch position of the transport path and the branch path to transport a sheet in either direction of the first tray or the branch path, a second transport roller positioned on the branch path to transport a sheet in either direction of the second tray or the transport path, and a control section recognizing a transport length of the sheet transported by the first transport roller and the second transport roller, and controlling the first transport roller and the second transport roller. The control section performs first and second transports for switchback-transporting a sheet.