PURPOSE: To minimize heat loss while reducing weight with larger freedom for mounting of a heating body by integrating the heat pipe section with the heating body mounting section with metal.

CONSTITUTION: Members 7a and 7c having a cylindrical section 8 as a cylinder is shape are used for basic elements to form a box-shaped structure as a whole in one cycle from the line A to the line B. A wick 1c and a working fluid 11 are sealed into the cylindrical section 8 to form a heat pipe. Joining portions as shown by the fat line are joined together with an adhesive, a revet, and a spot welding. A heating device 13 is placed at a flat plate section 9 integral connected with the heat pipe section thereby reducing the heat loss and due to the heat pipe construction, the necessary soldering section can be limited to the end as is among ordinary heat pipes thereby minimizing possible leakage. Though light, it resists the bending and compression substantially because of its box-shaped structure.