Abstract: The present invention relates to a method of computing a defocus amount in lithography and lithographic process using the method. A first step executes plural double-exposure operations each including a pattern exposure for forming a pattern of a predetermined line width and a full-area exposure over an area covering the pattern, employing different dosages employed in the full-area exposures for different double-exposure operations. A developing operation is performed. subsequent to the double-exposure, whereby a plurality of resist patterns are obtained. In a second step, the edge roughness and the line width are measured on each resist pattern. In a third step, a Gaussian function is fitted to the edge roughnesses and the line widths. The distribution width of the Gaussian curve is determined as the defocus amount of a pseudo-profile of the beam which indicates a change in lithographic factors that affect the accuracy of lithography.