A coolant composition for a fuel cell, including (a) an alkylene glycol, (b) deionized water, and (c) a compound containing a trimethylsilyl group. The compound containing a trimethylsilyl group of the composition of the present invention prevents the oxidation of the alkylene glycol, and thus the generation of an acid is 700 ppm or less. Additionally, the compound prevent the oxidation of the alkylene glycol, thereby inhibiting the generation of an ionic material, and thus the rate of change of electrical conductivity (conductivity after oxidation/initial conductivity) can be maintained to be 40 times or less. Therefore, the coolant composition for a fuel cell of the present invention can be used as a coolant for a cooling system of a fuel cell driving device with an electrical conductivity of 40 μs/cm or less even without being frozen in the winter.