PURPOSE: To prevent increasing of the temperature of liquid, by a method wherein the evaporating efficiency of the liquid is improved through the supply of the air so that an evaporating amount is maximized, the liquid and a heat generating body are separated away from each other by a baffle plate, and gas is caused to flow in from the liquid side.

CONSTITUTION: A heater 5 is electrically connected to increase the temperature of a wicking body 6 of a heat part, and the temperature of an evaporating part is increased to the desired evaporating temperature of the liquid. Thereafter, the air is fed in through a flow-in port 3 for gas. The air is fed to the evaporating part from the liquid side of a container 1 through a gap 9 between an opening A, through which the wicking body is inserted, of a baffle plate 8 and the wicking body 6. The width of the opening A is set to a value equivalent part. This constitution improves an evaporating efficiency, and installation of the baffle plate causes disconnection of the liquid from the heat generating body to cause gas to flow in from the liquid side, resulting in the ability to prevent increasing of the temperature of the liquid.