A retardation film, formed by stretching a film including a norbornene-based, ring-opening polymer containing a structural unit (A) represented by a formula (1), has high transparency, excellent wavelength dispersion characteristics in a single layer, is capable of providing specific retardation to broadband light, is extremely adhesive to other materials, is capable of attaining optical characteristics that are unique among negative birefringence characteristics, and is capable of providing a reverse dispersion of birefringence wavelength dispersion characteristics. The present invention also provides a liquid crystal display device using the foregoing film.