By carrying out circuit simulations, paretos that are non-dominated solutions in a solution specification space for respective items in the requirement specification are obtained for all of circuit configurations having possibility that requirement specification is satisfied, and a provisional optimal solution, which is on a pareto curved surface identified by the obtained paretos and whose distance with the requirement specification is shortest, is identified. Furthermore, a circuit configuration corresponding to the provisional optimal solution is identified and the provisional optimal solution is mapped to values of circuit parameters. Then, the pertinent circuit configuration and values of the circuit parameters, which are obtained by the mapping, are outputted.