COOLING SYSTEM OF FUEL CELL

PROBLEM TO BE SOLVED: To provide a fuel cell cooling system of such a structure that a primary side cooling liquid circulating passage for circulation of the primary side cooling liquid is connected with a cooling passage partitioned in a fuel cell, a circulation pump for circulation of the liquid is installed in this primary side cooling liquid circulating passage, and that a secondary side cooling liquid is allowed to make heat exchange with the primary side cooling liquid flowing in the primary side cooling liquid circulating passage so that cooling is accomplished, wherein gas is bled out of the primary side cooling liquid circulating passage to nullify the gas bite-in sound of the circulation pump. SOLUTION: A gas-liquid separating part 13 is formed in the primary side cooling liquid circulating passage 4, and a tank 15 is installed in communication with this part 13 through a gas bleeding passage 14 and put in communication with the primary side cooling liquid circulating passage through a cooling liquid return passage 16, and the gas bite-in sound of the circulation pump 11 is nullified by means of gas bleeding.