PURPOSE: To use a 35mm film small-diameter cartridge on the present camera and processing machine, in common, and simultaneously, to provide a erroneous load preventing means for a small-diameter cartridge.

CONSTITUTION: A constitution is adopted so that the present camera and photographic processing machines can be used as they are, by fitting an attachment 20 having the same width as the outer diameter of the present cartridge into the small-diameter cartridge 10. Further, in this relation, the constitution is adopted so that when the cartridge 10 is loaded on a camera in a state where the cartridge 10 has the fitting of the attachment 20 or is used independently, erroneous loading is capture-treated by the shape of the rib of a spool end part or the actuator projection 42 of a detector 41 provided in the cartridge room of the camera, as well.