To ensure that the production can be made in a factory, that the transportation with a track is easy, that the work on installation site is also simple, and that this can exhibit the performance enough.

An upper heat pipe 1a where a ferromagnetic edge 9 is inserted into an evacuated metallic pipe 7 and a magnet to attract the ferromagnetic edge 9 is attached to the periphery of the tip of the metallic pipe 7, and a lower heat pipe 1b where a refrigerant 14 is charged in the evacuated metallic tube 7 connected to this bottom are arranged two pieces lengthwise and are joined with each other, being sealed with a nut-shaped connecting metal fitting 15, on a installation field. Then, the magnet attached to the upper short heat pipe 1a is removed, and the ferromagnetic edge 9 is allowed to fall. Then, the block plates 11b and 11b at the junction part are punched by an impact, whereby the inside of both heat pipes 1a and 1b are made continuous to make one piece of heat pipe 1.