In an embodiment, a confidence interval of a yield is calculated with a set specification of an evaluation item and confidence level and values of the evaluation item obtained in Monte Carlo simulations to determine whether or not a target yield is within the confidence interval of the yield. In a case where the target yield is within the confidence interval of the yield, a Monte Carlo simulation executing unit is instructed to execute a subsequent Monte Carlo simulation. In a case where the target yield is not within the confidence interval of the yield, it is determined that the target yield will be achieved when a minimum value of the confidence interval of the yield is the target yield or larger while it is determined that the target yield will not be achieved when a maximum value of the confidence interval of the yield is below the target yield.