A power supply noise analysis model creation method comprising; obtaining a distance which appears most frequently, from among the distances from a vias judged to be the nearest to the vias, respectively, as a reference via pitch, generates four nodes for the via of target wherein the four nodes generates the middle point with the other four via that are near the via of the target, obtaining meshes which include the nodes, respectively, by dividing the power island structure and the power supply pair by dividing lines which pass between the generated nodes, and converting each of the meshes obtained to a circuit element equivalent to the mesh.