An apparatus is provided with a processing tray 42 to mount sheets ejected from an image formation section, aligning means (aligning plates 61, etc.) for aligning end portions of a sheet ejected on the processing tray 42, a post-processing apparatus 43 that performs binding processing on the sheets aligned by the aligning means, and moving means (unit moving motor 60, etc.) for moving the post-processing apparatus 43 to a plurality of post-processing positions set to perform the binding processing at different binding processing target position on the sheets, and moves the sheets to a post-processing undergoing position corresponding to the post-processing position substantially in parallel with a travel direction of the post-processing apparatus 43. It is thereby possible to perform the binding processing on the ejected sheets appropriately while implementing the apparatus compact in size.