To provide a fuel cell system, which can maintain a high circulation rate within the wide range amount of the fuel gas supplying flow.

It has a small ejector 104, which shows the high circulation rate when fuel gas has low flow amount by making off-gas from the fuel cell 108 circulate by making fuel gas as a driving flow, and a large ejector 105, which shows the high circulation rate when the fuel gas has except low flow amount by making the gas discharged from the small ejector 104 circulate by making the fuel gas as the driving flow. The introduction of the fuel gas to the small ejector 104 and the large ejector 105 is controlled according to the demand fuel gas flow amount of the fuel cell, so that an ejector circulation rate may become to a predetermined high circulation rate.

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