PURPOSE: To surely obtain a fine pattern with a good dimensional stability by providing a film contg. a specific sensitive diazonium salt on a resist film, and by exposing the obtd. film with a specific visible ray to form a pattern.

CONSTITUTION: The sensitive film contg. a sensitive diazonium salt is provided on a resist film followed by forming a pattern with a ray capable of exposing both the resist and the diazonium salt. The diazonium salt comprises the compd. shown by formula I or II wherein R1 and R2 are each hydrogen atom, halogen atom, alkyl, alkenyl or alkoxy group or group shown by formula III, R3WR8 are each hydrogen atom, halogen atom, alkyl or alkenyl group, X is anion capable of forming the diazonium salt. By forming the prescribed pattern by the visible ray having ≥400nm wavelength, a shade ability against UV makes large, and a fading rate due to light may be allowed to be coincide with the sensitivity of the resist so as to obtain a complete transparent film after fading, and to surely obtain the fine pattern having the good dimensional stability.