A cooling apparatus includes a tank for keeping a coolant liquid therein and having an air layer, a heat receiving element in contact with a heat generating part to receive heat therefrom, a radiator for radiating heat absorbed by a coolant liquid, and a circulating mechanism for circulating the coolant liquid from the heat receiving element through the tank and through the radiator again to the heat receiving element. The tank has a conduit forming area for forming a coolant liquid circulating conduit to pass through a middle position of the tank, and a narrow gap which divides the conduit forming area at the middle position of the tank.