Disclosed is a fuel cell system, which uses a dead end method and discharges impurities accumulated on the anode side while inhibiting the oxidation reaction of carbon.
In the fuel cell system 1, a fuel cell 2 operates while a passage 8 for a fuel off gas is closed. Impurities accumulated in the passage 8 are discharged when a purge valve 9 opens. When a cell voltage measured by voltage measurement means 11 is not lower than a predetermined value, the present invention activates purge limitation means 13 to avoid a purge. When a cathode potential at which carbon oxidation occurs is X and the maximum anode potential is Y, the predetermined value is equal to X - Y.