The present invention relates to a norbornene monomer, a polynorbornene derivative, a liquid crystal alignment film including the same, and a liquid crystal display device including the same. More particularly, the present invention relates to a norbornene monomer, a polynorbornene derivative, a liquid crystal alignment film including the same, and a liquid crystal display device including the same, which have an alignment property by photoreaction, excellent thermal stability and photoreactivity, the increased photo-reaction rate and reliability of the alignment film, thereby showing high manufacturing process efficiency.