PURPOSE: To reduce internal leakage for lengthening the life of a device in an air operated valve to partition a high pressure gas line or the like by uniting a normally closed and a normally opened air operated valve, and applying duplex seal to them for reducing the internal leakage.

CONSTITUTION: A normally closed air operated valve 1 and a normally opened air operated valve 2 are united, and the stem tips 4a, 4b of the valves 1, 2 are arranged oppositely to each other, and outside pipes are connected to connecting ports 3a, 3b provided in each of valves 1, 2. When the valves are wholly closed, high pressure air is led into the air leading port 6a of the valve 2 to push up a spring 5b for closing the valve. In this case, the stem tips 4a, 4b of the valves 1, 2 function as a seal to display the capacity of a duplex seal. On the other hand, when the valves are wholly opened, the air contained in the valve 2 is vented, and at the same time, the high pressure air is led into the air leading port 6a of the valve 1 to push up a spring 5a for opening the valve.