To ensure optical performance within a permissible range, making outward appearance excellent, and making binocular vision comfortable. In cases where a difference of prescription including dioptric power between the right and left eyes is equal to or more than prescribed, when curvature of a first refracting surface and a second refracting surface of the right and left spectacle lenses is designed, binocular vision balanced design such as selection of at least either of a first or second refracting surface out of the right and left spectacle lenses, or an intermediate curvature of the first and second surfaces of the right and left spectacle lenses according to a dominant eye ratio so that a difference between curvature of the first refracting surfaces of right and left spectacle lenses is within a prescribed range after the right and left spectacle lenses fulfill prescription conditions containing dioptric power respectively, and optical performance of the right and left spectacle lenses are within their permissible ranges respectively.