The present invention aims to provide a liquid crystal display device in which image sticking and stains are sufficiently reduced. The present invention relates to an alignment film including: a polymer, wherein the polymer is a polysiloxane or a polyvinyl and contains a silsesquioxane group. The present invention also relates to a polymer for use in the alignment film, the polymer containing a silsesquioxane group. The present invention also relates to a liquid crystal display device including: the alignment film; a pair of substrates; and a liquid crystal layer disposed between the substrates, wherein the alignment film is disposed between at least one of the substrates and the liquid crystal layer.