PURPOSE: To improve the accuracy of exposure position alignment in a scale- down type photomask by making the outside dimension of the pattern of the photomask same as the outside dimension of a photomask differing in exposure magnification from this.

CONSTITUTION: In a scale-down photomask 10, the outside dimensions l1 of a mask pattern encircled with a frame part 14 is set same as that of the other mask, and a required area 18 of a unit pattern 16 is enclosed with a light shielding part 19. Exposure is accomplished at a prescribed magnification by using only this area 18. Thereby, the difference in errors of total pitch occuring in the difference in the sizes of masks is obviated, and since this makes it possible to match the pattern 16 existing on the outer side of the part 19 and the pattern on a wafer and to align positions in this way, the accuracy is improved, and the combination use of the masks is made possible; further, the improvement in working performance is achieved.