PURPOSE: To perform not only the detection of the presence or absence of film in a camera but also the read of the code of a DX film with simple constitution by installing a switching means and an electric detecting means further to one contact member for reading a pattern applied on the surface of a cartridge.

CONSTITUTION: A contact pin for coming in contact with the common pattern of a DX code is projected from one part of the housing of a cartridge chamber. A conductor leaf spring whose tip is contact-shaped is fixed at the base part of the contact pin through an insulating member, and the leaf spring part of the contact pin and the contact part of the leaf spring form a switching means 101, then the contact pin and the leaf spring conduct respective electrical signals to an electric circuit through a lead wire. The same constitution is applied to five contacts for reading the DX code other than the common pattern. Then, a detection means 1O2b is connected to a contact means for grounding 110 so as to detect the potential of the means 110, and the presence or absence of the cartridge is detected based on the potential.