A method for manufacturing a polarizer includes forming a conductive thin film layer on a first surface of a substrate. The conductive thin film layer corresponding to a processing line is partially removed by a treatment laser beam irradiated along the processing line. The removing the conductive thin film layer forms a plurality of groove lines on a portion of the substrate from which the conductive thin film is removed and a plurality of striped lines formed on a portion of the substrate on which the conductive thin film remains between the groove lines.