The present invention aims to provide an alignment film capable of sufficiently reducing image sticking and stain in a liquid crystal display device, and a liquid crystal display device including a photo-alignment film and sufficiently reducing image sticking and stain. The alignment film of the present invention contains a polymer containing a nitrogen radical-containing group, and a photo-functional group. The nitrogen radical-containing group is preferably a hydrazyl radical-containing group represented by the following formula (I) or (II): wherein R1 is a direct bond or a divalent organic group; Me is a methyl group; and Bu is a butyl group.