PURPOSE: To provide a metal oxide film having the compsn. of a superconducting material on a substrate surface, by applying a coating compsn. consisting of a mixture composed of coating reactants contg. metals at prescribed ratios on the substrate surface kept at a prescribed temp. and subjecting the compsn. to thermal decomposition.

CONSTITUTION: The substrate consisting of glass, etc., is maintained at the temp., at which the metal-contg. coating reactants may be thermally decomposed to metal oxide. The coating compsn. consisting of the mixture composed of the coating reactants contg. the metals at the ratios adequate for forming the meal oxide film having the compsn. of the superconductive material is applied on the substrate surface. Compds. of La, Sr, Y, Ba, Cu, Bi, Pb, Sc, etc., are preferably used for the mixture described above. The coating compsn. is applied in the form of the soln. or vapor of the metal-contg. coating reactants. As a result, the mixture composed of the metal-contg. coating reactants is thermally decomposed and the ceramic oxide film having the compsn. of the superconductive material is formed on the substrate surface.