A fuel cell system comprises: a fuel cell (1); a water circulation channel (9) through which water involved in the operation of the fuel cell (1) circulates; a water circulator (10) for circulating water present in the water circulation channel (9); a heater (14) for heating the water circulation channel (9); first abnormality detectors (29, 30) for detecting a first abnormality on leakage from the water circulation channel (9); and a controller (16). The fuel cell system (301) executes a water circulating operation for circulating water present in the water circulation channel (9) by use of the water circulator (10) in order to prevent the water circulation channel (9) from freezing and a heating operation for operating the heater (14). The controller (16) is configured so as to, when the fuel cell system (301) stops due to the first abnormality detected by the first abnormality detectors (29, 30), inhibit the water circulating operation for preventing freeze-up and not to inhibit the heating operation for preventing freeze-up.
