PURPOSE: To easily recognize a finished line width only by observing the coincident spot on the same line of the edges of patterns on wafer by a microscope by arranging specific simple patterns for measuring a line width on a photomask.

CONSTITUTION: Plural pattern pieces 10 and 11 constitute pattern groups 10a and 11a, and those two columns are arrayed so as to be adjacent in the vertical direction of the pattern piece, and the plural pattern pieces 10 and 11 with the same prescribed line width are arrayed in parallel in a horizontal direction with equal intervals A and C in the pattern group 10a and 11a. Moreover, a sequence display pattern 12 for displaying the array sequence of the pattern pieces 10 is provided so as to be adjacent to the pattern group 10a so that a measurer can easily identify the array sequence of the pattern pieces 10. Then, those patterns are arranged so that the left edge of the pattern piece 10 and the right edge of the pattern piece 11 can be placed on the same line shown by dotted lines when the sequence display pattern 12 is '0'.