PURPOSE: To arrange properly the ends of wire rods in longitudinal direction by extrusion in an extruding billet in which many wire rods are arranged parallel in a copper pipe by forming the front ends of the wire rods to a concave surface and rear ends to a convex surface.

CONSTITUTION: A wire rod 4 made of Nb, Ti alloy etc. is coated with oxygen- free copper, and many such wire rods are lined up longitudinally and inserted into an oxygen-free copper pipe. A conical front end member 6 and a discoid rear end member 7 are provided on both ends and welded to the pipe 5 to form a billet for extrusion. By making the face of the front end member 6 facing the bundle of wire rods a convex surface, the end face of the bundle of wire rods is formed to a concave face, and by making the face of the rear end member 7 facing the bundle of wire rods a concave surface, the end face of the bundle of wire rods is formed to a convex face. A billet formed thus is extruded to make a composite wire. By this way, the end face of extruded wire rods 4 can be arranged properly in longitudinal direction and material yield of the composite wire can be improved.