The present invention relates to a polymer composition which contains (A) a photosensitive side-chain polymer that exhibits liquid crystallinity in a predetermined temperature range and has a repeating unit comprising a vertically aligning group, and (B) an organic solvent. The present invention provides: a liquid crystal alignment film which has excellent tilt angle characteristics, while being provided with alignment controllability with high efficiency; a polymer composition which enables the achievement of this liquid crystal alignment film; a twisted nematic liquid crystal display element; and a vertical field switching mode liquid crystal display element.