1. A three-dimensional modeling method of generating three-dimensional electronic data of a building structure, said three-dimensional modeling method comprising the steps of: (a) inputting a photograph of the building structure expressed by electronic data; (b) inputting a positional relation between a shooting position of the photograph and the building structure and a shooting parameter required to fit the photograph to an actual scene of viewing the building structure from the shooting position; (c) defining a planar shape of the building structure and the shooting position in a virtual space set for generation of the three-dimensional electronic data, based on the input positional relation, and arranging the photograph at a position specified by the input shooting parameter; and (d) mapping the defined planar shape in a direction of height to be matched with the photograph, so as to specify a shape of the building structure in the direction of height.