The present invention provides a three-dimensional object molding apparatus to mold a three-dimensional object by sequentially stacking a molding material including at least: an input section for inputting information including three-dimensional shape information of a target to be molded necessary to produce a desired molded object; a database for storing weight information per unit volume of one or a plurality of the molding materials; a parameter generating section for calculating a filling rate indicating degree of denseness/sparseness of the molding material, or a mixture proportion of a plurality of the molding materials, based on the information necessary to produce the desired molded object obtained from the input section, and the weight information of the one or plurality of the molding materials obtained from the database, and generating molding information for stacking the molding material according to the calculated filling rate and mixture proportion; and a molding section for stacking the molding material.