In the present invention, there is provided an optical proximity correction method including steps of: extracting a gate length distribution of a gate from a pattern shape of the gate of a transistor to be formed on a wafer; calculating electric characteristics of the gate; determining a gate length of a rectangular gate having electric characteristics equivalent to the calculated electric characteristics; calculating a corrective coefficient for describing an associated relationship between a statistical value of the extracted gate length distribution and the determined gate length; extracting a gate length distribution of a gate of a transistor by printing the design pattern, and calculating a gate length distribution representative value from the statistical value of the gate length distribution using the calculated corrective coefficient; and correcting the design pattern so that the calculated gate length distribution representative value will be a specification value.