PURPOSE: To enable even a computer of highly dense mounting to be forcibly cooled down so as to set a temperature inside a computer case to a virtual junction temperature adequate for a semiconductor by a method wherein an electronic cooler taking advantage of a Peltier effect is built in an electronic equipment, and the temperature inside the equipment case is controlled by the cooling power of the cooler concerned.

CONSTITUTION: An electronic cooler 2 composed of a cooling conductor 2c and others starts to absorb heat when a direct current power supply 2g supplies a current to the cooler 2. The heat absorption concerned can be optionally changed by varying metals 2a and 2b of the cooler 2 in material, size, and number, and a current in intensity, and the cooler 2 has such a thermoelectric power that it can refrigerate if necessary. Therefore, the material, the size, and the number of the metal plates 2a and 2b and the intensity of a current are properly selected corresponding to the heat release value of a computer to cool down the inside of the computer case to an optimal temperature conforming to the virtual junction temperature of the semiconductor in a computer. By this setup, an electronic equipment can be cooled down to a temperature lower than the outside air temperature, so that even a computer of highly dense mounting can be easily cooled by an electronic cooler of this design.