To optimize a parameter value of a control system as to prescribed performance.

In this control system WCSX, the optimum solution is found while conducting wide range optimization as to continuous value parameters KPX, KVX, KFX, even when a single peak property is not assured as to a change of an evaluation function serving as an evaluation reference for performance of the control system WCSX with respect to a change of at least one of the continuous value parameters KPX, KVX, KFX contained in the control system WCSX, and even when plural evaluation functions changing independently each other are defined. The optimized control system WCSX is realized thereby to enhance the aiming performance.