A method for manufacturing an optical filter for a stereoscopic image display device, the method comprising: forming a polymer layer on a substrate; photo-orientating the polymer layer by positioning a patterned mask above the polymer layer, positioning a polarizer above the patterned mask, and irradiating ultraviolet light onto the polymer layer from the upper side of the polarizer, while moving the polymer layer, thereby forming an alignment layer having different orientation directions in fine regions formed along a lengthwise direction of the polymer layer; and forming a retardation layer on the alignment layer, wherein a first stage pattern having at least one light transmission region and at least one light shield region which alternate in a first direction, and a second stage pattern having at least one light transmission region and at least one light shield region which alternate in the first direction are formed in the patterned mask, wherein the light transmission region and the light shield region of the first stage pattern and the light transmission region and the light shield region of the second stage pattern alternate with each other in a second direction vertical to the first direction so that the light shield region of the second stage pattern is positioned below the light transmission region of the first stage pattern and the light transmission region of the second stage pattern is positioned below the light shield region of the first stage pattern, wherein the polarizer has two distinguishable regions, each of which transmit differently polarized light to each other, wherein the patterned mask and the polarizer are positioned during the irradiation of the ultraviolet light on the polymer layer, such that the polarized light which passes through one region of the polarizer passes only through the light transmission region of the first stage pattern and is then irradiated onto the polymer layer, and the polarized light which passes through the other region of the polarizer passes only through the light transmission region of the second stage pattern and is then irradiated onto the polymer layer. forming a polymer layer on a substrate; photo-orientating the polymer layer by positioning a patterned mask above the polymer layer, positioning a polarizer above the patterned mask, and irradiating ultraviolet light onto the polymer layer from the upper side of the polarizer, while moving the polymer layer, thereby forming an alignment layer having different orientation directions in fine regions formed along a lengthwise direction of the polymer layer; and forming a retardation layer on the alignment layer, wherein a first stage pattern having at least one light transmission region and at least one light shield region which alternate in a first direction, and a second stage pattern having at least one light transmission region and at least one light shield region which alternate in the first direction are formed in the patterned mask, wherein the light transmission region and the light shield region of the first stage pattern and the light transmission region and the light shield region of the second stage pattern alternate with each other in a second direction vertical to the first direction so that the light shield region of the second stage pattern is positioned below the light transmission region of the first stage pattern and the light transmission region of the second stage pattern is positioned below the light shield region of the first stage pattern, wherein the polarizer has two distinguishable regions, each of which transmit differently polarized light to each other, wherein the patterned mask and the polarizer are positioned during the irradiation of the ultraviolet light on the polymer layer, such that the polarized light which passes through one region of the polarizer passes only through the light transmission region of the first stage pattern and is then irradiated onto the polymer layer, and the polarized light which passes through the other region of the polarizer passes only through the light transmission region of the second stage pattern and is then irradiated onto the polymer layer.