An Nb3A l multi-filamentary superconducting wire capable of realizing both stabilization of a superconducting state and increase in capacity is provided. The Nb3A l multi-filamentary superconducting wire includes a core (1) formed of copper or copper alloy and located at the center of the wire; a multi-filamentary superconductor layer (2) located around the core (1) and having filaments (4) containing Nb and A l as constituent elements embedded in a matrix (5) formed of copper or copper alloy; and a high resistance layer (3) located around the multi-filamentary superconductor layer (2), and is characterized in that a sectional area of the core (1) is at least 15% of the total sectional area of the core (1) and the matrix (5) and that the core (1) and the matrix (5) are formed of copper or copper alloy of at least 99.9% purity. <IMAGE>
