To provide energy saving, to shorten a time from operation starting until a temperature of a cooling reception object is brought into a stationary state, and to provide the stable operation of the cooling reception object from immediately after operation starting in cooling the cooling reception object by using a variable conductance heat pipe.

In the variable conductance heat pipe, a working fluid 6 and a non-condensible gas 8 are sealed in an airtight container 1 having a heat receiving part 2 and a heat dissipation part 4. The cooling reception object 9 is provided in the heat receiving part 2, and a heating value is applied to the heat receiving part during the standby of the cooling reception object 9.