A film cover covers an exposure surface of a film unit to lighttightly block an exposure opening and is ejected from a discharge port. A bending guide groove is formed on the outside of an accompanying prevention rib in a width direction of a cover member along the accompanying prevention rib. The bending guide groove tilts a side edge portion, which is a distal end portion of the film cover, and the portion outside the accompanying prevention rib, in a protruding direction of the accompanying prevention rib. Since the side edge portion is bent by the bending guide groove, the both side edges portions do not engage with the discharge port, and the film cover can be ejected smoothly from the discharge port.