Abstract: Disclosed is a method that may include the steps of: (a) previously acquiring information on defect positions of the optical film along the length direction of the optical film; (b) dividing the whole area of the optical film into a plurality of large calculation areas for deriving a plurality of cutting positions, based on a normal cutting distance condition and minimum cutting distance condition in the length direction, and the information on the defect positions of the optical film; and (c) determining the cutting positions from an area, in which none of the cutting positions are determined in the length direction of the optical film, among the plurality of large calculation areas.