Prior to molding, an initial position of at least one movable reference mark, provided in the vicinity of an object of manufacture, is measured by a first position measuring means, and the initial position of the movable reference mark is measured by a second position measuring means provided in a processing means. During the course of molding, measurement of a position of the movable reference mark is carried out by the first position measuring means and the second position measuring means. Then, based on the initial position of the movable reference mark prior to molding and the position of the movable reference mark measured by the first and second position measuring means during the course of molding, an optical beam irradiating position of an optical beam and a processing position of the processing means are corrected.