To provide an automatic valve gear devised such that opening and closing of a nozzle or the like of an extension hose tip is interlocked with a valve provided in a cock side.

In the automatic valve gear in claim 1, an automatic valve chamber 2 and a sub automatic valve chamber 3 are provided penetrating a main pipe 1 attached to a cock, and reciprocation of a valve element 4 provided so as to move in inner sides of both by change of pressure, opens and closes the valve. In the automatic valve gear in claim 2, an auxiliary valve chamber 15 is provided next to the automatic valve chamber 2, and reciprocation of an auxiliary valve 16 provided in an interior assists movement of the valve element 4. In the automatic valve gear in claim 3, in places of the automatic valve chamber 2 and the sub automatic valve chamber 3, elastic force of a bellows 24 is used, and reciprocation of the valve element 4 opens and closes the valve.