PURPOSE: To provide a long valve socket suppressing the increase of the number of part items and capable of being formed merely via a simple coupling action.

CONSTITUTION: A relay connector 2 is provided for a independently usable valve socket 1. The first connection section 23 couplable with the connector connection section 8 of the valve socket 1 is provided on one end side of the relay connector 2, and the second connection section 24 having a vertically opposite structure to the connector connection section 23 of the valve socket 1 is provided on the other end side. When the first connection section 23 is inserted into the connector connection section 8 while a lock arm 37 is warped and deformed, the lock arm 37 is elastically restored at the prescribed position, a hook projection 17 is coupled in a hook groove 38 and hooked on a hook face 39, and the valve socket 1 and the relay connector 2 are integrally assembled in the release stop state. A long valve socket having a long total length is formed.