According to an aspect of an embodiment, a method comprises a screw fastening unit extracting step of extracting a screw fastening unit, in which at least two or more members are fastened by a screw, from a three-dimensional model, a shape changing step of changing each of circular arc surfaces of the screw, a screw through hole, and a screw hole disposed in the screw fastening unit to a polygonal polyhedron approximating the circular arc surface, a mesh creation step of creating an analysis model which is divided into a meshed analysis unit by allocation of polyhedral meshes along each of the edge surfaces of the screw, screw through hole, and screw hole which is changed to polyhedrons, and a contact definition step of setting the friction of a contact unit of the mesh-divided screw and screw hole to be infinite so as to achieve a fixed state.