PURPOSE: To minimize the side etching by wet etching for forming a semi- additive pattern and easily form a mask pattern by dry etching at the time of forming the wiring pattern of a printed circuit board which is widely used for constituting circuits of various kinds of electronic equipment.

CONSTITUTION: A mask pattern 14 provided with a metallic film 14-4 which has the same shape as a wiring pattern and is baser than a panel metallic film 2 on the uppermost part is formed on the upper surface of the metallic film 2 formed on the surface of an insulating substrate 1 and, by wet etching the metallic film 2 simultaneously with the pattern 14, a wiring pattern 16 is formed on the surface of the substrate 1.