Sheet post-processing device

A sheet post-processing device connected to an image forming apparatus, the sheet post-processing device being successively fed with sheets on which images are formed by the image forming apparatus on the basis of input image data, the sheet post-processing device applying predetermined post-processing onto the fed sheet,

• the sheet post-processing device comprising:
• a staple unit configured to automatically form a cut-in tongue portion and a cut-in hole in a predetermined shape through a sheet bundle including a plurality of sheets, insert the cut-in tongue portion into the cut-in hole to join the sheets of the sheet bundle with each other, and staple the sheet bundle;
• sheet bundle discharge means configured to discharge the stapled sheet bundle;
• and
• a stacking tray configured to stack the stapled sheet bundle discharged,
• wherein a discharge position of the stapled sheet bundle discharged by the sheet bundle discharge means and a stacking position of the stapled sheet bundle with the stacking tray are set so that the stapled sheet bundle is dropped and stacked so that the stapled sheet bundle is overlaid in such a manner that the position of the stapled sheet bundle on the stacking tray is not displaced.