PURPOSE: To prevent lowering in heat conveying capacity of a flexible heat pipe by a construction wherein the peripheral wall of a metal pipe is projecte outwardly along the circumferential direction, and a cylindrical wick is inserted in the pipe and also wick retainers are located at space intervals therein.

CONSTITUTION: A metal pipe 10 forming the outer member of a heat pipe has peripheral walls projected partially outwardly so as to form spiral projections 11. Inserted in the metal pipe 10 is a cylindrical flexible wick 12 made of a metal gauze etc. which is retained by coiled springs 13 on the inner peripheral surface of the pipe 10 at regular intervals. The wick 12 is closely contacted with the inner peripheral surface of rectilinear portions of the pipe 10 between the projections 11 in a wide area, and therefore lowering in the heat conveying capacity of the flexible heat pipe can be prevented.