fifth aspect of the invention is characterized in that the inter-block power equivalent circuit creating step is a step of creating the circuit for analyzing the inter-block power wiring by adding the impedance information on the inter-block power wiring to the degenerate impedance circuit created by the functional block power equivalent circuit creating step and that the analysis step uses as the equivalent circuit at least one of the degenerate impedance circuit and the circuit for analyzing the inter-block power wiring. The sixth aspect of the invention is characterized in that the inter-block power equivalent circuit creating step is a step of creating the circuit for analyzing the inter-block power wiring by adding the impedance information on the inter-block power wiring to the degenerate impedance circuit created by the functional block power equivalent circuit creating step