To employ a general working tube for piping which may be conventionally often used, to simply protect an electric wire by the tube, and to form a coupling body in simple structure, in a coupling for a pneumatic piping additionally functioning as electric wiring.

A coupling body 1 is provided with a tube connection port 6 and an electric wire lead-out port 7. The tip part of a tube 8 for a pneumatic piping is connected to a tube connection port 6, an electric wire 12 is inserted in the hollow part 15 of the tube 8. The electric wire 12 is led out from the electric wire lead-out port 7 from the internal part of the coupling body 1 and the electric wire 2 is fastened by a nut 13 for fastening through a sealant 18.