To provide a sheet post-processing device which is equipped with a plurality of post-processing units which executes post-processing and a sheet loading section, and capable of suppressing reduction in the productivity of an image forming apparatus when post-processing is not executed.

On downstream side in a sheet transfer direction of a receiving transfer path, a punch unit 250 is provided on one end side of a sheet P, and a staple unit 280 is provided below the punch unit 250. A post-processing tray 210 is provided in a direction orthogonal to the sheet transfer direction of the staple unit 280. Further, a proof tray 600 to which the sheet P transferred on the receiving transfer path is loaded is provided on the downstream side in the sheet transfer direction of the receiving transfer path. A link mechanism is provided for raising or lowering the proof tray 600 according to whether post-processing is executed or not; the link mechanism guides the sheet P transferred from the receiving transfer path to a predetermined stop position when post-processing is executed and guides the sheet to a loading surface 601 of the proof tray 600 when post-processing is not executed.