A catch type sheet tray for accommodating sheets sequentially driven out of an image forming apparatus by catching the leading edges of the sheets. The tray has a transport unit for transporting the sheet driven out through the outlet downward. A holder receives the sheet conveyed by the transport unit by catching the leading edge of the sheet while causing the trailing edge of the sheet to hand down to the outside. A mounting section mounts the transport unit on a portion of the apparatus from which the horizontal tray has been removed. The catch type tray is mounted on the apparatus in place of the horizontal tray.