Method for producing a retardation film, an optical film, an image display device, a liquid crystal display device, and a phase difference film

And to provide a manufacturing method and the like of the retardation film contributes to cost reduction and larger screen visibility good liquid crystal display device. Ends conveyed while holding the elongated polymer film that is continuously fed, a method for producing a retardation film to be stretched in the transverse direction to the conveying direction while conveying the polymer film, wherein the retardation film is one having an optical property that satisfies 0.1 ≦ NZ ≦ 0.9 and having an orientation angle in a direction transverse to the conveying direction of the film, a polymer film is slack in the conveying direction , method for producing a retardation film, which comprises stretching the polymer film in the transverse direction are provided.