Sheet post-processing apparatus and image forming system having the same

A sheet post-processing apparatus provided in an in-body space between a reading unit that reads an image of a document and an image forming unit configured to form the image read by the reading unit on a sheet, the sheet post-processing apparatus comprising:

• an introducing port which introduces the sheet on which the image is formed;
• a conveying device configured to convey, in a conveying direction, the sheet introduced from the introducing port;
• a processing tray on which the sheet conveyed by the conveying device is placed;
• a manual inserting unit provided at a position different from the processing tray and capable of manually inserting a sheet from the outside of the sheet post-processing apparatus;
• a binding processing device configured to perform a binding process on the sheet placed on the processing tray or the sheet inserted into the manual inserting unit;
• a slide mechanism capable of pulling out, in the conveying direction, the sheet post-processing apparatus from a fixing position where the sheet post-processing apparatus is fixed in the in-body space;
• a fixing unit configured to fix the slide mechanism into the in-body space and to fix the slide mechanism to a conveying position where the sheet is conveyed to the conveying device;
• and
• a release lever provided at a position overlapping with a placing range of the sheet set on the manual inserting unit and configured to release the fixing unit.