PURPOSE: To eliminate trouble in the wire fabrication process and manufacture a superconducting wire material of high current density by performing a heat treatment at a certain temp. during the cold wire dia. processing for a certain period of time.

CONSTITUTION: Cu powder, Cu-Sn powder, and powder of Nb and Nb-Ti alloy are mixed thoroughly, embodied in a certain shape by hydraulic press, and put in an Nb pipe fully, and the resultant is subjected to such process as hydrostatic pressure extrusion, cold swager processing, cold rolling, drawing and the like. On the way of such cold processing, a 150-400°C heat treatment is made at a certain stage for a period no longer than 10min. This eliminates wire material breakage during wire fabrication, e.g. breakage of a thin wire of 1mm or less in dia., and the wire material shape is so uniform that the Cu and Sn powder parts and Nb part are axial symmetrical in the corss-section of the processed wire.