PURPOSE: To permit a panel to be controlled so as to have a uniform temperature distribution, by a method wherein all of heat pipes in different directions are embedded into the panel.

CONSTITUTION: An embedded heat pipe 5 and the embedded heat pipe 6 are connected in a panel, however, one of these heat pipes is laid on top of the other. Fins 9, 10 improve the heat transfer efficiency of the heat pipe, reduce the size of the heat pipe and become reinforcing members in the structure thereof. According to such a structure, the heat pipes in different directions can be embedded into both skin members opposing to each other so as to have the structure of a sandwich whereby a heat resistance due to an adhesive agent for attaching the heat pipe to the skin member of the side of attaching an equipment so far may be eliminated and a heat transfer characteristic between the equipment attaching side skin member and an outer skin member for radiating heat toward the outside may be improved.