To obtain efficiency over a wide range including conceptual design by applying respective reference data inputted to parameters of design rules based upon inputted specification and implementing the design rules in sequence.

A design rule data base 1 is stored with different kinds of design rules having operation contents as to one operation unit prescribed in a parametric. A user interface 2 inputs and stores a design rule in the design rule data base 1 and inputs specification of which kind of design rule stored in the design rule data base 1 is used and reference data applied to the parameter of the design rule to be used. A design rule execution module 3 applies the inputted reference data to the parameters of the design rules based upon the inputted specification to implement the design rule in sequence while referring to design information on standard components, design table data, a design calculation expression, and a machine performance table, etc.