PURPOSE: To allow electrical connection to be simultaneously made by letting fluid pass through with a piping fitted in a pipe coupling, in a pipe coupling device made up of the piping and the pipe coupling in which the piping is fitted detachably.

CONSTITUTION: The electrical wires 30 and 31 of an electric wiring 20 from a detection switch 16 detecting the position of the piston 2A of a fluid cylinder 2, are electrically connected to terminal members 28 and 29 which are pressed in an fixed onto the main body member 27 of a pipe coupling 3. Ends 28C and 29C of the terminal member 28 and 29 are positioned in the flow passage 9 of the pipe coupling 3, the mounting of a pipeline 21 onto the pipe coupling 3 permits the conductive members 23 and 25 of the pipeline 21 to be capable of coming in contact with the end sections 28C and 29C of the terminal members 28 and 29, so that electrical connection is thereby made.