PURPOSE: To improve the critical current density by setting to satisfy a specific relation between the diameter of an NbTi filament and the area occupying rate of artificial pins, and setting the intervals between the artificial pins making coincident to the maximum operating magnetic field of a superconducting wire.

CONSTITUTION: Plural vertical holes 2 are engraved on an NbTi ingot 1 in island form (in the condition separating in the same intervals), Nb rods 3 as artificial pins are inserted to the holes 2, and the product is entered in a CuNi alloy tube 4 so as to form a primary billet 5, and the primary billet 5 is made into a primary wire material with the hexagnal section by a hot extrusion and a wire drawing process. And the diameter df of an NbTi filament, the area occupying rate of the artificial pins in the NbTi filament, and the interval ds between neighboring pins are composed to satisfy an empirical formula to obtain the maximum superconductivity in the maximum operating magnetic field. Consequently, a maximum superconductivity can be obtained in the maximum operating magnetic field.