A apparatus includes a unit to operate a first dose of a beam corrected for a proximity effect for each of second mesh regions of a second mesh size obtained by dividing the first mesh size by a product of a natural number and a number of passes, by using a dose model using a dose threshold; a unit to operate a representative temperature rising due to heat transfer originating from irradiation of the beam by using a dose for an applicable pass of the first dose and a unit to operate a polynomial having a term obtained by multiplying a dose modulation coefficient based on the representative temperature by a pattern area density as an element, and a dose that makes a difference between a value obtained by operating the polynomial and the dose threshold within a tolerance is used.
