PURPOSE: To shorten drastically a cooling time at the time of manufacturing of a mold made of resin and molding of plastic also, by a method wherein a metallic pipe is installed within the mold made of the resin by laying the same in the mold.

CONSTITUTION: A metallic pipe is positioned and fixed before casting of a resin part, after casting and curing or casting and curing of the resin part, a groove or a hole is hollowed out by cutting, into this part of which a metallic pipe is inserted, when a resin compounding product is cast again for back-filling, a space between a metallic pipe and the resin part is free from defective thermal conductivity. After installation of the metallic pipe, curing of the resin compounding product is performed by circulating a heating medium within the metallic pipe. When the mold made of the resin for which the metallic pipe manufactured like this is used for molding of plastic, since cooling is fast, the whole of a molding cycle is reduced.