FUEL CELL SYSTEM

A fuel cell system includes a fuel cell (34), a reforming portion (33), a water reservoir (14), a condenser (12), a water supply pipe (42) supplying water to the water reservoir, a water supply valve (43) opening and closing the water supply pipe, a pump (11b2), a low position detection sensor (45a) detecting an abnormal level (C3), a high position detection sensor (45b) detecting a normal level (C1), and a control apparatus (15) controlling an output of the fuel cell to be in a steady state in a case where the high position detection sensor detects the normal level, the control apparatus reducing the output of the fuel cell in a case where the low position detection sensor does not detect the abnormal level and the high position detection sensor does not detect the normal level.