1. A three-dimensional model retrieval apparatus comprising. a model normalizing means for rotating and/or translating a three-dimensional model so that main axis directions of the three-dimensional model are consistent with coordinate axes of a three-dimensional space, and barycenter of the three-dimensional model is consistent with origin of a system coordinate system; a two-dimensional image generating means for projecting said three-dimensional model respectively in a positive direction and a negative direction of each coordinate axis of said system coordinate system to generate a plurality of two-dimensional images; a model describing means for generating a model descriptor of the three-dimensional model from said two-dimensional images; and a retrieving means for retrieving, based on said model descriptor, a three-dimensional model which most matches an input query from a model database.