PURPOSE: To enable the efficient cooling of an electronic module, where the temperature of the electronic module is made small in dispersion by a method wherein not only a metal mesh is loaded in a cooling pipe provided in contact with the electronic module but also a coolant feed pipe is provided in parallel with the cooling pipe, and the cooling pipe and the coolant feed pipe are connected together through two or more capillaries.

CONSTITUTION: A solenoid valve 8 is operated through an instruction for the start of cooling to release a high pressure bomb 8 loaded with boiling coolant of a high pressure, and high pressure liquid phase boiling coolant is sent to a cooling pipe 3 loaded with a metal mesh through a coolant feed pipe and two or more capillaries 5. When the high pressure boiling coolant flows into the cooling pipe 3 through the capillaries 5, it adiabatically expands to become a low temperature coolant in two phases of vapor and liquid and absorbs the heat released from electronic components inside the electronic module 1 placed in contact with the cooling pipe 3 through a latent heat occurred when a liquid phase coolant vaporizes, and then is discharged into the air through a pressure regulating valve 7 provided to adjust an evaporation point of the coolant.