PURPOSE: To obtain an excellent oxide superconductor with the fiber strength of 1MPa or above and the ductility of 0.5% or above by using the fiber spinning technique and the ceramic molding technique.

CONSTITUTION: A material containing (La, Ba)2cCuO4 or expressed by a general formula LnBa2Cu3O7-x (where Ln is one kind of Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, Eu, Sm and 0<x≤0.5) or containing Y2O3, Y(NO3)2 or the like, BaCO3, Ba(NO3)2 or the like, CuO, Cu(NO3)2 by heat treatment is pulverized to the grain size of 0.2μm or below, it is dispersed in a polymer binder of polyvinyl alcohol copolymer or the like into fibers and baked to remove the binder, and fibers with the fiber strength of 1MPa or above, preferably 5MPa or above, the ductility of 0.5% or above, preferably 2.5% or above, and the porosity of 10vol.% or below are obtained. Oxide superconducting fibers with the critical temperature of 80K or above and the critical current of 10A/cm2 or above in the nonmagnetic field are obtained according to this constitution.