The present invention relates to a retardation film that comprises a blend resin of 1) an acryl-based copolymer resin that comprises an alkyl methacrylate-based monomer and a cycloalkyl methacrylate-based monomer, and 2) a resin that comprises an aromatic ring or aliphatic ring in a polymer main chain, a method for manufacturing the retardation film, and a liquid crystal display device that comprises the retardation film. The retardation film according to the present invention has excellent heat resistance, optical transparency, mechanical strength, and durability.