PURPOSE: To obtain a mask which can be used independently of the type of a photosensitive resin, by making the outside circumference and the inside circumference of a mask pattern shorter than those of a pattern formed on an object to be worked and piling these patterns.

CONSTITUTION: Dimensions of the outside circumference and the inside circumference of a mask pattern (b) are set to values smaller than those of a pattern (a) formed on an object to be worked, and the region interposed between the outside circumfernce and the inside circumference of the mask pattern is set to a dark part, and the other part is set to a bright part. When patterns are piled up, the outside circumference of the pattern (a) of the object to be worked is seen but the inside circumference is not seen, and patterns are aligned by the outside circumference. Consequently, the mask for photoetching is obtained easily which can be used whether the type of a photosensitive resin is negative or positive.