A light shield plate 12 having outer openings 14 and 15 is fixed to the outside of a cartridge body 11 in which inner openings 18 and 19 for exposing a photosensitive recording medium 4 to the outside are formed. A shutter 13 for opening and closing the inner openings 18 and 19 is incorporated movably between the cartridge body 11 and the light shield plate 12. Closing-side ends 55e and 55f of the shutter 13 and shutter-closing-side edges 18a and 19a of the inner openings 18 and 19 and/or shutter-closing-side edges 14a and 15a of the outer openings 14 and 15 are inclined from each other.