The method comprises a number of simultaneously switching signals calculation step in which the number of simultaneously switching signals is calculated for each set of user setting information for the input and output signal on the basis of pin arrangement information and the user setting information of the pins in a neighboring area of a pin to be executed in the estimation process; and a simultaneous switching noise calculation step in which a difference is calculated between noise corresponding to an initial point and that to a terminal point in a range of the number of simultaneously switching signals calculated for each set of user setting information on the basis of a relationship between the number of simultaneously switching signals and the noise caused by the number of simultaneously switching signals for each set of user setting information.