To ensure and stabilize electric connection between a plug and a receptacle constituting a connector suitable for a small type of a thermocouple with simple structure, to enhance reliability for the connection, to easily and surely assemble them in a small space, and to attain overhaul repair and effective utilization.

Connector main bodies 12, 13 are stored inside a pair of cases 1, 2 arranged oppositely. Pin plugs 22, 23 for connecting electrically a conductor 33 are mounted on one side of the connector main body 12. Receceptacles 26, 27 for connecting electrically thermocouple element wires 35, 36 are mounted on the other connector main body 13. The pin plugs 22, 23 are connected to the receptacles 26, 27 extractably. The pin plugs 22, 23 and the receptacles 26, 27 are composed of a material same or similar to that of the thermocouple element wires 35, 36. Plural slits 29 are formed axis-directionally in portions of the peripheral faces of the receptacles 26, 27 storing the pin plugs 22, 23. Outer diameters of the peripheral faces of the receptacles 26, 27 are made expandable. Coil springs 32 are detachably attached to in the peripheral faces of the receptacles 26, 27.