To provide a nitrogen monoxide feeding means with a safety mechanism securing the safety for a patient if a gas permeable membrane is broken, and provide a nitrogen monoxide feeding means at a low cost by achieving the safety mechanism with a simpler structure.

The nitrogen monoxide feeder has a conduit with a gas passage for a gas to flow in the lumen and a gas permeating means mounted at the top of the conduit as a communicating means for feeding nitrogen monoxide or a gas containing nitrogen monoxide into a blood vessel from the outside of an organism, The gas permeating means comprises a gas storage part of the closed system mounted between the lumen of the conduit and the blood vessel, a first gas permeable membrane interposed between the gas storage part and the lumen of the conduit, and a second gas permeable membrane interposed between the gas storage part and the blood vessel.