Provided is a liquid crystal alignment agent which is capable of providing a pretilt-angle by photo-alignment-method and providing a liquid crystal alignment with excellent ageing-stability of the pretilt-angle. The said liquid crystal alignment agent comprises a radiation-sensitive polyorgano siloxane obtained from reacting specific polyorgano siloxane having epoxy group and (A) cinnamic acid derivate with (B) specific compound having photosensitizing structure selected from preferable acetophenone structure, benzophenone structure, anthraquinone structure, biphenyl structure, carbazole structure, nitro-aryl structure, fluorene structure, naphthalene structure, anthracene structure, acridine structure and indole structure.
Liquid crystal alignment agent, polyorgano siloxane, liquid crystal alignment film and method for forming the same as well as liquid crystal display element