PURPOSE: To attain efficient optimum design of the system by selecting a specific model with a common means depending on a parameter characterizing the system and extracting each preset performance evaluation means.

CONSTITUTION: A specific model is selected by a common selection means 1 depending on a parameter characterizing the system being an object and each performance evaluation means 30 corresponding to the model is extracted and an individual quantitative data relating to the system is entered to apply performance evaluation by using a common calculation means 4. Moreover, the evaluated result is outputted by using the common means or stored or extracted optionally as required. Thus, the optimum design of the system is implemented efficiently.