A manufacturing method for a mold die used in a molding process for obtaining a mold used to form an eyeglass lens having at least first and second reference points and having an area where power continuously changes, wherein, in the molding process, a glass material placed on a molding surface of the mold die is softened by heat to form an upper surface of the glass material by letting a lower surface of the glass material closely contact the molding surface, the manufacturing method comprising: a design data making step of making design data for the molding surface of the mold die based on predetermined prescription information; a molding surface creation step of creating the molding surface in accordance with the design data; an error amount specifying step of specifying error amounts at first and second corresponding points defined on the created molding surface respectively corresponding the first and second reference points, with respect to design values by the design data; a first correction surface defining step of defining a first correction surface to be over laid on an entire molding surface based on an error amount specified at the first corresponding point; a second correction surface defining step (S23, S24) of defining a second correction surface to be over laid on the entire molding surface based on the first correction surface and an error amount specified at the second corresponding point, wherein the second correction surface has no power at the first corresponding point; a design data correction step of combining a design surface by the design data, the first correction surface and the second correction surface, and corrects the design data based on combined data after the combining; and a corrected surface creation step of creating the molding surface in accordance with the corrected design data, wherein trial and error by the error amount specifying step, the first correction surface defining step, the second correction surface defining step (S23, S24), the design data correction step, and the corrected surface creation step is repeated until each of the error amounts converges within a tolerance. a design data making step of making design data for the molding surface of the mold die based on predetermined prescription information; a molding surface creation step of creating the molding surface in accordance with the design data; an error amount specifying step of specifying error amounts at first and second corresponding points defined on the created molding surface respectively corresponding the first and second reference points, with respect to design values by the design data; a first correction surface defining step of defining a first correction surface to be over laid on an entire molding surface based on an error amount specified at the first corresponding point; a second correction surface defining step (S23, S24) of defining a second correction surface to be over laid on the entire molding surface based on the first correction surface and an error amount specified at the second corresponding point, wherein the second correction surface has no power at the first corresponding point; a design data correction step of combining a design surface by the design data, the first correction surface and the second correction surface, and corrects the design data based on combined data after the combining; and a corrected surface creation step of creating the molding surface in accordance with the corrected design data, wherein trial and error by the error amount specifying step, the first correction surface defining step, the second correction surface defining step (S23, S24), the design data correction step, and the corrected surface creation step is repeated until each of the error amounts converges within a tolerance.