NOVELTY - The fuel cell system comprises first and second airflow generation parts including first and second fans (16, 18), a fuel cell (7) having first and second surfaces faced to each other, a housing to receive the fuel cell, and a control unit (10). The fuel cell includes a cathode-side plate having air flow paths, an anode-side plate having fuel flow paths, and a membrane electrode assembly arranged between the cathode-side and anode-side plates and in contact with the air flow paths and the fuel flow paths. The first and second fans generate the first and second cooling airflows respectively.    USE - Used as a fuel cell system such as a direct methanol fuel cell (DMFC) system, molten carbonate fuel cell (MCFC) system and polymer electrolyte fuel cell (PEFC) system.    ADVANTAGE - The fuel cell system is capable of effectively realizing the cathode air supply function using a part of the cooling air thus enabling reduction in size, low cost and ease of control.    DETAILED DESCRIPTION - The fuel cell system comprises first and second airflow generation parts including first and second fans (16, 18), a fuel cell (7) having first and second surfaces faced to each other, a housing to receive the fuel cell, and a control unit (10). The fuel cell includes a cathode-side plate having air flow paths, an anode-side plate having fuel flow paths, and a membrane electrode assembly arranged between the cathode-side and anode-side plates and in contact with the air flow paths and the fuel flow paths. The first and second fans generate the first and second cooling airflows respectively. The air flow paths have first openings at its ends, which are arranged on the first surface, and second openings at its other ends, which are arranged in the second surface. The housing includes first and second ducts having inner surfaces and defining first and second cooling flow paths between the inner surfaces and the first and second surfaces respectively, where the first and second cooling airflows flow through the first and second cooling flow paths respectively. The first cooling flow path is communicated with the second cooling flow path through the air flow paths. The control unit is configured to control a pressure difference between the first and second cooling airflows in the first and second cooling flow paths respectively and to control airflows introduced from the first cooling flow path into the air flow paths in accordance with the pressure difference. The control unit controls the rotations of the first and second fans, and controls a flow rate of each of the first and second cooling airflows in accordance with a predetermined cooling amount required to cool the fuel cell and a predetermined supply amount of air to be supplied into the air flow paths. A valve is provided in one of the first and second cooling flow paths, where the control unit controls the valves to adjust an internal pressure in the cooling flow path. A resistance part is provided in one of the first and second cooling flow paths, and equalizes distributed flows of the supply air flowing from the cooling flow path into the air flow paths. A flow resistance is provided in one of the first and second cooling flow paths, partially branches the cooling airflow flowing through the cooling flow path into distributed flow, and adjusts the distributed flow into the air flow path. An INDEPENDENT CLAIM is included for a method of controlling a cooling airflow for a fuel cell.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic block diagram a fuel cell system.    Fuel tank (2)    Fuel supply unit (4)    Temperature sensor (6)    Fuel cell (7)    Control unit (10)    First and second fans. (16, 18)