1. A system for generating a parts catalog by using three-dimensional model data of a plurality of parts, the system comprising: an image generating unit that generates a part image of a part from among the parts and an assembly image in which all part images are assembled based on the three-dimensional model data; a data output unit that calculates boundary data related to a position and a shape of each of the parts in the assembly image based on the three-dimensional model data; a catalog generating unit that generates the parts catalog of a desired part by combining the part image of the desired part, the assembly image, the boundary data of the desired part, and parts configuration data indicative of data for parts management; and a receiving unit that receives boundary data of a data-missing part that is a part whose three-dimensional model data is not available, wherein the image generating unit displays an image of a predetermined-shaped part in a corresponding position of the assembly image based on the boundary data of the data-missing part.