PURPOSE: To improve adhesion between element wires and a critical current density without causing disconnection by a cold forging wire drawing system, by performing a cold forging treatment at least one time for seven times of wire drawing work die passing.

CONSTITUTION: The raw material 2 for wire drawing, in which an Al core is surrounded by an Nb layer, is supplied to wire drawing dies 3, 31, 32, and 33 from a supply roll 1. The raw material 2 is thinned into a fine line 21, 22 and 23 in order by a surface reduction ratio of 5-25% per die, and then is passed through a cold forging machine 4 at least one time for seven times of wire drawing work die passing to be wound on a winding roll 6 for providing an element wire 5.