For cooling of an electronic equipment, a heat receiving jacket, to which piping extended outside the electronic equipment is connected, is mounted to a heat generating element in the electronic equipment, a radiator, a cooling-liquid tank, a pump, and a pipe, which joins them, are constructed as an external module, and the external module is mounted externally and fixed to a housing of the electronic equipment. Cooling liquid is circulated by the pump through the heat receiving jacket, the radiator, and the tank to achieve cooling.