11 respectively the grounding pin 18 and the contact pin 19 are insulated from the lens mount 14 by respective insulating members 18a and 19a and electrically connected to a control circuit 40 on the lens side the grounding pin 26 and the contact pin 27 are connected to a control circuit 50 on the camera body side in the mount member 20 as constructed above according to the present invention the mount body having a complex contour can be easily and inexpensively injection molded furthermore the reinforcing ring member 22 has a simple shape and accordingly can be inexpensively made of metal consequently as a whole the manufacturing cost can be remarkably reduced while ensuring necessary strength and precision since the mount surface 21a is made of synthetic resin no sound is made during the sliding contact of the mount surfaces 21a and 15 in particular since the engineering plastic has a high strength is highly corrosion proof and highly wear proof there is no change in the friction characteristics despite repeated attachment and detachment fig6 through 8 show a second embodiment of the present invention in this embodiment the reinforcing ring member 22 in the first embodiment mentioned above which is embedded in the mount body 21 is replaced with a fastening type of reinforcing ring.