Method of manufacturing fine filamentary NB-TI based alloy superconducting wire

A method of manufacturing a fine multifilamentary Nb-Ti based superconducting wire was disclosed, which comprises a first step of processing an alloy consisting essentially of 10 to 50 atomic % of niobium, 40 to 75 atomic % of titanium and no higher than 30 atomic % of least one element selected from a group consisting of hafnium, tantalum and tungsten to form an alloy wire, a second step of covering said alloy wire with a stabilizer, cold drawing the resultant wire, bundling a plurality of stabilizer-clad wires thus obtained, covering the bundle of wires with a stabilizer, and extruding and cold drawing the resultant bundled wire to thereby form a multifilamentary wire, and a third step of thermally treating the resultant multifilamentary wire at a temperature of 2500 to 6000 C. and drawing the resultant treated multifilamentary wire to a reduction rate of 30 to 99.9%. The third step is carried out more than once