PURPOSE: To enable operation under the optimum conditions for a heat transfer capacity, by arranging an unwettable porous structural body between a vapor channel and a condensation region.

CONSTITUTION: A vapor channel 46 is provided in a housing 12 and an unwettable porous structural body 50 is arranged between the vapor channel 46 and a condensation region 30. The pore dimension of the structural body 50 keeps a condensed liquid 34 from passing and instead, a condensed liquid path 56 is provided to guide the condensed liquid 34 to an evaporation channel 24 from the condensation region 30. Thus, despite any effect of gravity, the stream 34 of the condensed liquid toward the evaporation region 24 is maintained to prevent the operation of a heat pipe 10 being kept dry in the evaporation region 24, thereby enabling operation under the optimum conditions with respect to a heat transfer capacity.