FUEL CELL SYSTEM

A fuel cell system includes a fuel cell module (20) performing a power generation and discharging an exhaust combustion gas generated by the power generation, a water storage tank (31) storing water that serves as a storage water, a storage water circulation line (32) at which the storage water circulates, a storage water circulation pump (32a) provided at the storage water circulation line and driven by an electric motor, a heat exchanger performing a heat exchange (33) between the exhaust combustion gas and the storage water, an air bubble detection portion (S102) detecting a generation of air bubbles at the storage water circulation line and a control unit (60) controlling the storage water circulation pump to stop operating for a predetermined time period in response to an air bubble detection signal generated by the air bubble detection portion and to resume the operation of the storage water circulation pump.