An optical alignment method which develops a pretilt angle by batch plane exposure without tilting a substrate. This optical alignment method provides liquid crystal aligning capability to the surface of a polymer film by exposing the surface of the polymer film through a slit exposure mask while the surface of the polymer film and the slit exposure mask are moved relative to each other substantially at a fixed rate. Alternatively, liquid crystal aligning capability is provided to the surface of the polymer film by exposing the surface of the polymer film through an optical exposure pattern while the optical exposure pattern having a plurality of lines with a certain width at certain intervals is formed on the surface of the polymer film continuously.