A pattern verification method includes preparing a desired pattern and a mask pattern forming the desired pattern on a substrate, defining at least one evaluation point on an edge of the desired pattern, defining at least one process parameter to compute the transferred/formed pattern, defining a reference value and a variable range for each of the process parameters, and computing a positional displacement for each first points corresponding to the evaluation point, first points computed using correction mask pattern and a plurality of combinations of parameter values obtained by varying the process parameters within the variable range or within the respective variable ranges. The positional displacement is a displacement between first point and the evaluation point. The method further includes computing a statistics of the positional displacements for each of the evaluation points, and outputting information modifying the mask pattern according to the statistics.