To avoid pressure variation in a cooling water channel, extend a life of an ion exchange resin used to maintain quality of cooling water and reduce power consumption by auxiliary machinery at low cost. There is provided a polymer electrolyte fuel cell, a cooling water tank, a cooling water channel, a cooling water pump, a heat exchanger, a fuel-side condenser and an oxidizer-side condenser that cool exhaust fuel gas and exhaust oxidizer gas discharged from the fuel cell to condense content water vapor, a condensed water tank that stores the water condensed in the fuel-side condenser and the oxidizer-side condenser, a water supply channel having a water supply pump for feeding the condensed water to the cooling water tank, and a water discharge channel for the cooling water tank.