To release the locking of a cartridge cover when photographic film is projected from a cartridge main body.

An upper gear 31 provided on a lower gear 33 meshed with a partial gear 25a provided in a locking member 25 through a vertical shaft 32 and integrally rotated with the gear 33 sets a driving member 30 at a position where a light shielding cover 15 is closed interlocked with setting the member 25 at a locking position by the lever operation of an operation lever, and sets the member 30 at a position where the cover 15 is closed interlocked with setting the member 25 at a locking release position. A pin 31b moved by the rotation of the gear 31 is erected on the gear 31. When the photographic film is projected from the cartridge main body 12, the locus of the pin 31b is intercepted by a projected line 34b provided on an exposed frame number display board 34 so as to regulate the rotation of the gear 31. Then, the member 25 is regulated at the locking position so as to inhibit the locking of the cartridge cover 5 from being released.