PURPOSE: To enlarge a lot and to improve an adhesive strength by sealing different kinds of metals into a metallic pipe, and thereafter, joining them by a hot hydrostatic pressure press, and reducing the diameter.

CONSTITUTION: A round bar or a powder of a nickel-iron alloy is put into a large-sized copper pipe, and a vacuum sealing is executed, heating it for degassing. Subsequently, it is heated in a hot hydrostatic pressure press so that it becomes a temperature right below a melting point of copper, also pressed to a prescribed atmospheric pressure, and the copper and the nickel-iron alloy are diffused and joined by executing a heat treatment for a prescribed time. Next, forging and hot working of hot rolling are executed, and thereafter, wire drawing and intermediate annealing are repeated, and a "Dumet" wire of a prescribed size is manufactured.