An optical element having an optical film (100, 10) comprising first and second base films (110, 150) disposed to face each other; and a light modulation layer existing between the first and second base films (110, 150), wherein electrode layers (120, 140) are formed on the surfaces of the first and second base films (110, 150) that face each other, respectively, and each of the electrode layers (120, 140) comprises a first region formed to be capable of applying an electric field to the light modulation layer, and a second region connecting each of the electrode layers (120, 140) to an external power source so that the first region can apply the electric field, wherein the second region on the first base film comprises A and B regions formed at opposite edges of the first base film, respectively, and the second region on the second base film comprises C and D regions formed at opposite edges of the second base film, respectively, the A region and the C region face each other, and the B region and the D region face each other, wherein the optical element is formed so that it can switch between a gradation mode in which the A and C regions or the B and D regions are connected to the external power source to generate an electric field in the first region, and a uniform transparent mode in which the A and D regions or the B and C regions are connected to the external power source to generate an electric field in the first region, wherein the optical element further comprises a transmittance control means comprising electrode terminal parts in each second region, wherein the external power source is connected to each second region via the electrode terminal parts, characterized in that the transmittance control means further comprises a driving means capable of selecting two electrode terminal parts and connecting the external power source to said electrode terminal parts, in that the transmittance control means is configured to perform a conversion of the gradation mode and the uniform transparent mode by selecting the respective electrode terminal parts, and in that the light modulation layer is an active liquid crystal layer comprising a liquid crystal host and an anisotropic dye guest, and capable of switching between at least two differently oriented states. wherein electrode layers (120, 140) are formed on the surfaces of the first and second base films (110, 150) that face each other, respectively, and each of the electrode layers (120, 140) comprises a first region formed to be capable of applying an electric field to the light modulation layer, and a second region connecting each of the electrode layers (120, 140) to an external power source so that the first region can apply the electric field, wherein the second region on the first base film comprises A and B regions formed at opposite edges of the first base film, respectively, and the second region on the second base film comprises C and D regions formed at opposite edges of the second base film, respectively, the A region and the C region face each other, and the B region and the D region face each other, wherein the optical element is formed so that it can switch between a gradation mode in which the A and C regions or the B and D regions are connected to the external power source to generate an electric field in the first region, and a uniform transparent mode in which the A and D regions or the B and C regions are connected to the external power source to generate an electric field in the first region, wherein the optical element further comprises a transmittance control means comprising electrode terminal parts in each second region, wherein the external power source is connected to each second region via the electrode terminal parts, characterized in that the transmittance control means further comprises a driving means capable of selecting two electrode terminal parts and connecting the external power source to said electrode terminal parts, in that the transmittance control means is configured to perform a conversion of the gradation mode and the uniform transparent mode by selecting the respective electrode terminal parts, and in that the light modulation layer is an active liquid crystal layer comprising a liquid crystal host and an anisotropic dye guest, and capable of switching between at least two differently oriented states.