NOVELTY - Fuel cell system comprises water distribution condition estimating unit that estimates and acquires water distribution condition of fuel cell; state-of-charge acquiring unit that acquires state of charge of storage device; determining unit that sets favorable combination range as combination range in which combination of water distribution condition of fuel cell and state of charge of storage device is suitable for required power of vehicle; and combination status improving unit that improves water distribution condition of fuel cell using storage device output.    USE - Fuel cell system used for vehicle.    ADVANTAGE - The fuel cell system effectively generate output power though power allocation between fuel cell and storage device. By performing power allocating operation, combination status can be maintained within favorable combination range, and moisture content of fuel cell can be controlled to preferable level closer to optimum range.    DETAILED DESCRIPTION - Fuel cell system comprises water distribution condition estimating unit that estimates and acquires water distribution condition of fuel cell; state-of-charge acquiring unit that acquires state of charge of storage device; determining unit that sets favorable combination range as combination range in which combination of water distribution condition of fuel cell and state of charge of storage device is suitable for required power of vehicle, according to predetermined criteria, and determines whether actual combination of acquired water distribution condition and acquired state of charge is within favorable combination range; and combination status improving unit that improves water distribution condition of fuel cell using storage device output when actual combination is not within favorable combination range, thus moving actual combination within favorable combination range. The combination status improving unit operates air compressor that supplies purge gas when state of charge of storage device is at insufficient level and water distribution condition of the fuel cell is an excessively high humidity condition. An INDEPENDENT CLAIM is included for controlling fuel cell system by estimating and acquiring water distribution condition of fuel cell; acquiring charge state of storage device; setting favorable combination range; determining whether actual combination of acquired water distribution condition and acquired state of charge is within favorable combination range; and improving water distribution condition of fuel cell using output of storage device.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of a process for effective power allocation between fuel cell and storage device.