To provide a joining structure of a heat pipe and a plate which is hardly affected by the relative surface roughness of the plate and enables reduction of a joining heat resistance to the utmost by an easy method.

In the structure wherein the heat pipe and a fin material or the like are joined in a part or the whole of the heat pipe, the fin material or the like has a groove into which the heat pipe is inserted, and at least either the heat pipe or the joining surface of the fin material or the like is subjected to surface treatment with solder.