To form an optical alignment film having large anchoring strength in a liquid crystal display device of an IPS system and to suppress an AC residual image of the liquid crystal display device.

A polyimide to be a rigid high polymer and a polyimide to be a soft high polymer are mixed to be used in an alignment film material on which optical alignment treatment is applied. The material easily generates rotation of an oligomer after emission of polarizing ultraviolet thereon, and can improve dichroic ratio of UV absorption of an alignment film. Thus, anchoring strength by the alignment film to liquid crystal is strong, and an AC residual image can be suppressed.