A mold is prepared in which the use surfaces of the upper and lower molds are the design curved surfaces of an optical lens having a spherical shape. The curved surface shape of the optical lens formed using this mold is measured. The measurement values are approximated to a formula (1) of aspherical surface, and the curved surface of the molded optical lens is specified as an aspherical surface. Information on the error between the specified curved surface of the optical lens and the design curved surface is recorded as correction information in a database for each characteristic of the optical lens. Using the correction information recorded in the database, the design values of the use surfaces of the upper and lower molds for molding the optical lens having an aspherical curved surface are corrected thereby to design an optical lens.