<p>Disclosed is a retardation film mainly composed of an acrylic polymer having transparency, heat resistance and high retardation property. Specifically disclosed is a retardation film mainly composed of an acrylic polymer, wherein the in-plane retardation per a thickness of 100 µm at a wavelength of 589 nm is not less than 130 nm but not more than 500 nm, and the total light transmittance is not less than 85%. This retardation film preferably has a glass transition temperature of not less than 110°C but not more than 200°C. The acrylic polymer as the main component of this retardation film preferably has a lactone ring structure.</p>
