Design variable value sets for predetermined design variables are generated, and for each of the predetermined design variables, parameter value sets for predetermined parameters are generated. For each combination of them, circuit simulation is carried out to obtain a performance item value set for predetermined performance items. Then, for each of the design variable value sets, and further for each of the parameter value sets generated for a corresponding design variable value set, combinations of the design variable value set and parameter value set are identified, for which performance item values for all of the predetermined performance items are not less than performance item values obtained for a combination of the corresponding design variable value set and a corresponding parameter value set, and a yield rate is calculated by dividing the number of identified combinations by the number of parameter value sets generated for the corresponding design variable value set.