Abstract: Input of only circuit configuration data of datapath section cells constructing datapath section leads to an automatic determination of configurations at cell level of peripheral circuit corresponding to the datapath section for subsequent determinations of the layout of datapath circuit layout from configuration data and netlists of the peripheral circuit, the datapath section cells and the standard cells. It is not necessary to prepare the peripheral circuit function descriptive library according to the configuration data of the datapath sections. This facilitates the creation of the layout of the datapath circuit and reduces the necessary time for creating the same because all the descriptive levels may be unified to the cell level.