Patent ID: 8563189

Claim:
A fuel cell system comprising: a plurality of single-cell units, each of which include an electrolyte membrane disposed between an anode and a cathode and which generate electric power by a reaction of a fuel gas in the anode and an oxidizer gas in the cathode; a fuel cell in which the plurality of single-cell units are stacked; a plurality of voltage measurement devices that measure the voltages of the single-cell units, respectively; and a control unit programmed to determine the humidification state of the fuel cell based on the voltage of a second single-cell unit disposed in the vicinity of a first single-cell unit, the first single-cell unit having a voltage that is equal to or lower than a predetermined voltage, wherein when the voltage of the second single-cell unit is equal to or lower than a predetermined insufficient-humidification-determining voltage which is higher than the predetermined voltage and is stored in the control unit, the control unit is programmed to determine that humidification of the fuel cell is insufficient.