A sheet post-processing apparatus which includes at least one sheet receiving bin for receiving the sheets; a sheet discharging device for discharging the sheets into the sheet receiving bins; and a post-processing device for port-processing the sheets stored in the sheet receiving bins; a support for supporting the sheet discharging means, for movement between a first location for discharging the sheets into the sheet receiving bins and a second location at a predetermined distance away from the first location; and a moving device for moving the sheet discharging device from the first location to the second location when relative movement is imparted between the sheets and the post-processing device so that the post-processing device is activated at a predetermined location along the edges of the sheets in the sheet receiving bins.