The fuel cell system according to this invention disposes a moisture exchanger
(30) at a suction side of an air supply device (7). This causes an
increase in the pressure differential and temperature differential of the fresh
air and the cathode exhaust in the moisture exchanger (30) and promotes
transfer of moisture. Since the moisture exchanger (30) effectively transfers
moisture, it is possible to downsize the radiator for the cooling water and the
condenser (60). Thus it is possible to reduce the weight and size of the
fuel cell system.