The purpose of the present invention is to provide a hydrogen gas supply device comprising a pressure regulating valve capable of controlling the flow rate (or pressure) of hydrogen to a fuel cell stack with high accuracy and preventing hydrogen gas leakage into the atmosphere even when the upstream-side pressure is high. A hydrogen gas supply device (1) for supplying hydrogen gas to a fuel cell stack (3) comprises an electromagnetic pressure regulating valve (14) for regulating the pressure of the hydrogen gas to low pressure. The electromagnetic pressure regulating valve (14) is provided with a housing (21), and a valve passage (22) that connects a primary port (21a) and a secondary port (21c) are formed therein. In the housing (21), a valve element (24) for controlling the degree of opening of the valve passage is provided, and a high-pressure seal member (28) and a low-pressure seal member (29) are disposed on the outer periphery of the valve element (24). The high-pressure seal member (28) and the low-pressure seal member (29) are disposed in this order from one end side to the other end side of the valve element (24), and the electromagnetic pressure regulating valve is further provided with a housing-side pressure equalizing passage (34) that connects a buffer chamber (30) formed between the high-pressure and low-pressure seal members and the secondary port (21c).
