PURPOSE: To obtain a homogeneous Sn-Ta alloy having the prescribed composition ratio by adding and melting powdered Ta to and in molten Sn at a temp. in a specific range in an inert-gas atmosphere and then carrying out casting at a temp. in a specific range.

CONSTITUTION: A high frequency melting furnace, etc., capable of holding an inert-gas atmosphere are used. Pure Sn is melted, and powdered Ta is added to the resulting molten Sn at 700-1800°C and melted. Subsequently, the above molten Sn is agitated and held for the prescribed length of time, and, after slag is removed from the molten metal surface, casting is carried out at 650-1800°C. By this method, the homogeneous Sn-Ta alloy containing 0.3-6.0wt.% Ta can be obtained. This alloy is used for the production of commercial Nb3Sn superconducting wires.