To realize efficient correction with high accuracy by using an optimum correction division size when a pattern of a phase shift mask is subjected to optical proximity correction.

In the method for manufacturing a phase shift mask having a light shielding pattern to form a predetermined exposure pattern and having a shifter disposed in both sides of the light shielding pattern so as to transmit light in different phases from each other, the boundary position of the light shielding pattern and the shifter is divided by a unit having a predetermined pitch, and boundary position is subjected to optical proximity correction by each divided unit. The pitch as the division unit is preliminarily prepared as a waviness correction table TB according to the width and height of the shifter, and the correction is carried out by using the optimum division unit from the waviness correction table TB.