PURPOSE: To uniformly join port parts with high dimensional accuracy and the joint surfaces thereof by subjecting the joint surfaces of the port parts to ultrasonic welding, then subjecting the joint surfaces of the different inclinations of a cartridge body to ultrasonic welding.

CONSTITUTION: A spool 5 wound with a film 6 is fitted into a notch 16 and is held in a casing 3. A casing 4 is thereafter mounted to the casing 3 and the casings are pressed and fixed. The 2nd port part 12 is irradiated with ultrasonic waves from an arrow A direction. The contact surfaces of projections 13 and grooves 14 is melted in this way and the joint surfaces of the 1st port part 11 and the 2nd port part 12 are uniformly welded with the high dimensional accuracy. The contact surfaces of the projections 7 and the grooves 8 melt when the casing 4 is irradiated with the ultrasonic waves from an arrow B direction. The joint surfaces of the casing 3 and the casing 4 are uniformly welded by pressing and fixing. The specified spacing between spools 15 is maintained with this photographic film cartridge. The front end of the film 6 is, therefore, smoothly delivered to the outside of a cartridge body 2 by the rotation of the spools 5.