To form an optical alignment film having large anchoring strength and suppress an AC afterimage of a liquid crystal display device, in a liquid crystal display device of an IPS mode. In an alignment film material subjected to optical alignment processing, polyimide which becomes a rigid high molecule and polyimide which becomes a flexible high molecule are mixed and used. The material of the present invention can easily rotate oligomer after irradiating polarized ultraviolet rays and improve a UV-absorbed two-color ratio of an alignment film. Accordingly, an anchoring strength for liquid crystals by the alignment film is large to suppress an AC afterimage.