PURPOSE: To provide a film mounting and taking out mechanism for a camera using a film cartridge with a light shielding door.

CONSTITUTION: At the position shown in a figure of an actuating lever 80, a cartridge chamber 12 is locked at a housing position by a locking lever 75, and a light shielding door opening and closing key 22 is at an opening position and a cartridge light shielding door is opened and a cartridge supporting shaft and a fork support a spool. When the actuating lever 80 is slid in a direction A by a driving cam 95, a projection 32a engaging with a groove part 84 rotates a turning lever 32 in a clockwise direction, and the light shielding door opening and closing key 22 is rotated through a sector gear 32b and a gear 31 and the light shielding door is closed. When the actuating lever 80 is slid further in the direction A, the cartridge supporting shaft is detached from the spool and also a fork gear is detached from the fork. Then, the cartridge chamber 12 is released from the locking lever 75, so that a mounting position projected from the camera is obtained.