Abstract: An object is to provide a fuel cell system having a simple structure, which is capable of supplying gas appropriately through an ejector in accordance with the load of a fuel cell. The fuel cell system (1) uses an ejector (24) disposed in a gas supply system (4) to combine a new gas to be supplied to the fuel cell (2) with an off-gas discharged from the fuel cell (2) and supply the fuel cell (2) with the resulting combined gas. The ejector (24) includes a nozzle (46) for ejecting the new gas and generating a negative pressure for aspirating the off-gas, and a flow rate control mechanism (47) for controlling the flow rate of the new gas which passes through the nozzle (46). A first flow path (81) for leading the off-gas to the flow rate control mechanism (47) is provided in the gas supply system (4), and the flow rate control mechanism (47) controls the flow rate of the new gas in accordance with the pressure of the off-gas led from the first flow path (81).

Abstract: A valve in which durability of a sealing member made from an elastic material can be increased and sealing capability can be advantageously maintained over a wide range from a large differential pressure to a low differential pressure. A valve (100), in which a valve disc (1) and a valve seat (2) are brought into close contact via a sealing member (5) composed of an elastic material and provided at the valve disc (1) or valve seat (2), comprises a throttle section (30) defined by the shape of at least one of the valve disc (1) and valve seat (2). The throttle section (30) narrows a flow passage formed between the valve disc (1) and valve seat (2) and is provided near the sealing member (5). The flow passage narrowed by the throttle section (30) is so set that narrowing preferentially proceeds in the flow passage in close proximity to the sealing member (5) during the closing operation of the valve disc (1).