PURPOSE: To facilitate mounting/demounting work while eliminating the assembling work by composing a converter of two parts, i.e., a socket and a plug-in unit, stopped at a stopping part and connected through a connecting tube and an electric connector.

CONSTITUTION: The converter is composed of two parts, i.e., a socket 6 provided with a wire 7 from a system to be measured and a pressure hose 13 and a plug-in unit 5 provided with a detector 16 and an electric circuit part 17. The unit 5 and socket 6 are stopped at a stopping part and a channel communicates with a tube 13 through a tube 10. A sheath 8 and the socket 6 are provided with more than electric connector 14. After the socket 6 is assembled, failure can be checked by simply replacing the unit without requiring dismantlement. Consequently, a pressure converter can be mounted/demounted by single operation and assembling work can be eliminated.