Abstract: According to the present invention, in optical modeling method and apparatus of preparing a cubic resin model by curing ultraviolet-ray curable resin under irradiation of a laser beam thereon, for the sake of automatically correcting a dimensional difference caused by superfluous curing due to a transmitting laser beam by automatically detecting the bottom of an overhang portion or a modeling product on surface shape data, the dimensional difference is corrected automatically on the surface shape data through a method in which vertexes of polygonal patches constituting the surface shape data are replaced with nodes, nodes constituting a polygonal patch lying at the overhang portion bottom are moved by a correction amount obtained from a value conforming to an inclination of the patch plane to change the shape and position, and modeling is carried out on the basis of the data.