PURPOSE: To ensure sheet registering by forming an inward bulging edge on the lower side of sheet registering ruler plate separated from a tray and disposing this edge to oppose to the end face of tray side at the ruler plate side with the upper surface being located below the tray surface.

CONSTITUTION: A sheet P delivered from an output unit 100 is received in a swingable sheet collecting tray 6 to be located and registered by sheet registering ruler plates 7, 8 arragned at right angle to each other and separately from the tray 6. These registering ruler plates 7, 8 are formed on the lower sides with inward bulging edges 7a, 8a which are opposed to the end face of the tray side while the upper surfaces 7a', 8a' are located below the upper surface 6' of the tray. Thus, before the sheets are registered by both ruler plates 7, 8, the sheet edge enters between boundary gaps d1, d2 between the tray and ruler plate to prevent the stagnation of sheets, ensure the sheet registering and improve reliability of the device.