To suppress dimensional fluctuation of a transfer pattern within an allowable range and to improve the yield of products and the throughput.

A birefringence index calculation device 11 calculates distribution of RBI as an index representing changes in the polarization state between incident light entering a photomask and exiting light exiting from the photomask, originating from the incident light. Then a selection device 21 selects a mask blanks based on the distribution of the calculated RBI and on the allowable value of dimensional fluctuation in a pattern transferred onto a photoresist film formed on a wafer.