An alkaline fuel cell having an electrolyte, and anode and cathode electrodes disposed on two sides of the electrolyte is provided. A fuel cell system has this fuel cell, a discharge passageway that is connected to a discharge opening of the fuel cell and that discharges from the fuel cell an exhaust fuel containing unreacted fuel, and a circulation passageway that is connected to an introduction opening for introducing the fuel into the fuel cell and that circulates and supplies the exhaust fuel to the fuel cell. The fuel cell system further includes fuel/water separation means linked to the discharge passageway and the circulation passageway and disposed between the discharge and circulation passageways. The means separates and removes water from the exhaust fuel flowing in from the discharge passageway, and then causes a concentrated fuel from which water has been separated and removed to flow into the circulation passageway.