To provide a self-excited oscillation type heat pipe capable of improving the heat transportation efficiency by the capillary action without preventing the self-excited oscillation for the stability of the performance.

The heat pipe is characterized by a number of fine fins 10 continuously formed in the length direction on the inner surface of a metal capillary 1. It is preferable that the ratio (h)/ (di) of the height (h) of the fin 10 to the inner diameter (di) of the capillary 1 is 0.01-0.35, and the ratio (n)/(di) of the number of the fins (n) to the inner diameter (di) of the capillary is 3-25. It is also preferable that the lead angle θ to the tube axis in the fin 10 is 0-20°, and the inner diameter of the capillary 1 is 0.5-5 mm.