To provide a heat transport device having high heat transport capability and heat transport efficiency suitable for miniaturization and thickness reduction.

The heat transport device 1 has gas phase paths (5A, 5B), and a plurality of liquid phase paths (6A, 7A) as flow paths connecting evaporating parts (3A, 3B) and condensing parts (4A, 4B), and has structure generating capillary force which the evaporating parts circulates working fluid. Performance decrement and malfunction caused by the interfusion of the gas phase into the liquid phase paths are prevented thereby. The liquid phase paths are made so that the cross sections are gradually small from condensing parts toward evaporating parts, and this prevents the gas phase being mixed into the liquid phase paths since the capillary force of the liquid phase paths can be made large. Since a wick part and liquid phase paths of the vicinity are filled with the working fluid of the liquid phase even after dry-out, stable operation can be realized.