A CMOS model generating apparatus 1 according to the present invention generates a CMOS model by converting an In-Ip space into an xn-xp space such that a typical condition TT and corner conditions FF, SS in the In-Ip space become (0, 0), (α, α) and (−α, −α) in the xn-xp space, determining an ellipse fitting to the respective mappings of the corner conditions FF, SS, FS and SF with the mapping (0, 0) of the typical condition TT as a center, expressing two independent principal components in the form of a Gaussian distribution using the major and minor axes of this ellipse as axes of the principal components, and obtaining a probability distribution determining deviations of the Gaussian distribution such that the cumulative probability within this ellipse becomes equal to the one presumed by the corner conditions FF, SS, FS and SF.