Abstract: A gas flow valve is provided in a pressure operated part to obtain an air flow velocity conforming to a change in pressure. A main body comprises a resilient member and is tapered from a base end to a distal end thereof to form a wedge-shaped portion at the distal end. In use, surfaces of the wedge-shaped portion serve as pressure-responsive surfaces, and gas is fed through a linear slit formed in the tip of the wedge-shaped portion and a passageway extending longitudinally within the main body and communicating with the slit. The slit is provided with a flapper comprising a thin sheet-like member formed to have a plurality of projections on a distal end thereof and oriented in such a manner that the projections are situated in the slit.