Provided is a heat pipe, which has a simple construction but an excellent heat transfer performance. A loop-type heat pipe (1) has a loop-shaped fluid moving route, in which an evaporation portion (2), a vapor-rich pipe portion (4), a condensation portion (3) and a liquid-rich pipe portion (5) are sequentially connected. A nozzle portion (6) and a diffuser portion (7) are formed in that loop-shaped fluid moving route. As a result, a difference is made between the forward fluid resistance and the backward fluid resistance of the loop-shaped fluid moving route, thereby to form a one-directional steam flow in the loop-shaped fluid moving route.