To improve manufacturing efficiency of a semiconductor device by automatically deciding the overlay accuracy of an exposure pattern.

A second retrieving part 2b retrieves lens distortion fluctuation between aligners to which mix and match are applied, from a distortion control storing part 6b, and retrieves overlay accuracy between previously measured aligners, from an inspection data control storing part 6c. An operating part 2c calculates the deviation of true overlay accuracy. A deciding part 2d compares the calculated true overlay accuracy with the specification of overlay accuracy of the process from a specification control storing part 6a, decides whether the true overlay accuracy is within overlay specification, and displays the result on a display part 5.