PURPOSE: To obtain an oxide superconductor having high critical current density, by applying a magnetic field to a mixture of oxide superconductor powder and liquid oxygen to effect the orientation of the superconductor powder and fixing the powder in the oriented state.

CONSTITUTION: Powder of an oxide superconductor such as a lamellar perovskite-type oxide composed of rare-earth element-Ba-Cu-O is prepared beforehand. The oxide superconductor powder is mixed with liquid oxygen at a low temperature and a magnetic field is applied to the obtained fluid from external source. Since liquid oxygen is ferromagnetic, it is attracted to a magnetic pole and the oxide superconductor crystal powder is oriented by Meissner effect in the direction to cross the magnetic flux with the c-plane of the crystal. After the completion of the orientation treatment, the orientation is fixed e.g. by compression molding with a mold to obtain the objective oxide superconductor.