1. A method for measuring dimensions of a fine pattern, comprising: calculating a surface area and determining a profile of a displayed pattern image; calculating a center of gravity in the pattern image; calculating an equivalent diameter of a circular pattern having the same surface area as the pattern image; calculating a mathematical mean value of pattern lengths of lines which all pass through the center of gravity of the pattern image and which intersect the pattern image at two points of the profile, said pattern lengths being defined as distances between the two points; and comparing the means value with the equivalent diameter of the circular pattern image.