To provide a gas supply valve whereby safe and sure action can be performed without receiving an influence by environmental variation due to vibration, heat, etc., during running of a vehicle, in the gas supply valve used in a vehicle driven by an engine with natural gas serving as fuel.

In this gas supply valve for a gas power vehicle, in a main unit 1, a turnable upper shaft 2 and a lower shaft 3 vertically moved by turning the upper shaft 2 are arranged. By moving down the lower shaft 3, a valve unit suspension support shaft 6 suspended to a suspension metal fitting 9 fixed to a lower end face of the lower shaft 3 is pressed down, an opening lower end of a center hole 5c of a valve unit 5 inserting this suspension support shaft 6 is opened, a gas pressure adjusting chamber 8 is formed between the valve unit 5 and the lower shaft 3 through the through hold 5c, and gas in a gas vessel A is allowed to flow in the chamber 8. In this way, a gas pressure inside/ outside the valve unit 5 is equalized, from this condition, by making the lower shaft 3 further movable, the valve unit 5 is pressed down, simultaneously with opening a gas inflow port 4, a gas flow path 14 provided in the lower shaft 3 is made to communicate with the gas pressure adjusting chamber 8 and a gas supply passage 41, and gas is supplied to an engine side.