PURPOSE: To remove only the mask pattern formed on a thin film without any influence on the thin film, and thus obtain a good quality thin film pattern, by employing a material insensitive to ultraviolet radiation for the thin film, and using resist sensitive to ultraviolet radiation in photoetching.

CONSTITUTION: Resist, soluble in organic solvent and insensitive to ultraviolet radiation, is applied to a substrate 1 to form a thin film 2 there. A photoresist layer 3 sensitive to ultraviolet radiation is formed thereon. A photomask 4 is placed on the photoresist layer 3, and the workpiece is exposed to ultraviolet radiation UV. Then it is immersed in developer and thereby patterned. Using the patterned photoresist layer 3 as a mask pattern, the thin film 2 is etched to form a specified pattern. The entire surface of the photoresist layer 3 is exposed to ultraviolet radiation UV. The workpices is immersed in developer to remove the photoresist layer 3, and to obtain the thin film 2 formed on the substrate 1 in a specified pattern.