To provide a sheet post-processing device in which a plurality of post-processing units which can execute post-processing are arranged side by side in a vertical direction on one end side parallel to a sheet transfer direction in receiving a sheet or a sheet bundle, and which is capable of accurately maintaining a position of post-processing which is executed to the sheet or the sheet bundle by upper post-processing units.

A punch unit 250 and a staple unit 280 are provided respectively above and below a position on a downstream side in a sheet transfer direction of a receiving transfer path 500. A post-processing tray 210 is provided in a direction orthogonal to the sheet transfer direction of the staple unit 280. A guide member 602 for the other end, which supports the other end side facing the one end side of a sheet P from below in the case of passing the sheet P to the punch unit 250, is provided. Further, clamp units 400 having clamps 401, which grip the one end side of the sheet P and move on a track orthogonal to the sheet transfer direction, are provided from the punch unit 250 to the staple unit 280.