A sheet processing apparatus performs folding processing so that one end of a sheet exists inside the folded sheet. The sheet processing apparatus includes a transport path to guide a transported sheet, a rotating body pair capable of transporting the sheet in a first direction to perform folding processing, and in a second direction for switching back the sheet subjected to the folding processing, a folding blade that pushes the sheet to a nip portion of the rotating body pair, a press member that presses the sheet folded by the rotating body pair in the second direction, and a shift section that shifts the press member for pressing the sheet. In switching back the sheet, a control section controls transport of the sheet so that the one end of the sheet is halted within a region between the press member and a guide face of the transport path.