PURPOSE: To make a disconnecting motion to remove a socket from a pin device very much easy and certain by installing a prescribed engagement portion which can engage with the socket in a disconnecting direction at one of a pin device and a socket.

CONSTITUTION: A engagement portion 10 which can engage with a socket 9 in a disconnecting direction is installed at any one of a pin device 5 and the socket 9. It is thereby possible to operate the socket 9 in a disconnecting direction and do that operation certainly and easily by engaging such a tripper as a pair of tweezers, etc., whose tip portion is bent with the engagement portion 10 when the socket is disconnected from a pin device 5.