PURPOSE: To obtain a thin-walled and long-sized composite metallic bar having satisfactory joining property by superposing different kinds of metallic bars, cold rolling the same at a specific draft, heating continuously the rolled bar and subjecting the bar to hot rolling followed by cold rolling.

CONSTITUTION: Metallic bars are drawn out of long-sized bars 1, 2 of different metals and are superposed. The superposed bars are cold rolled and welded with pressure at ≥30% reduction ratio with a rolling mill 3 to form a cladding material 4. The material 4 is passed through an induction heating furnace 6 and is continuously heated after the material is coiled on a coiler 5 or directly after said rolling. The material 4 is hot rolled and welded with pressure with a rolling mill 7, by which the material is securely welded with pressure. The cladding material is thereafter cold rolled to form a composite metallic rod having a desired thickness.