PURPOSE: To achieve a good heat transfer by forming a screw thread on the inner circumferential wall of the unit body, and rotating the heat pipe unit.

CONSTITUTION: The heat pipe unit 1 is rotated on its axis by a rotating means 10. The sealed refrigerant 4 is evaporated by being heated on the high temperature side 8 of the heat pipe unit 1 to become the evaporated gaseous refrigerant, which moves to the low temperature side 7 where it releases heat to be condensed to become the condensed liquid refrigerant 5. Since the heat pipe unit 1 is rotated, the condensed liquid refrigerant 5 moves toward the high temperature side 8 along the screw thread 4 in the inner circumferential wall 3 on account of the centrifugal force, where it is heated again to be evaporated for transmission of heat.