An optical film in which a retardation film is laminated on one side of a polarizing plate, in which a transparent protective film is laminated on both sides of a polarizer, so that an absorbing axis of the polarizing plate and a slow axis of the retardation film may be perpendicular or may be parallel to each other, wherein a value Nz represented by Nz=(nx.sub.1-nz.sub.1)/(nx.sub.1-ny.sub.1) satisfies a range of 0.4 through 0.6, and an in-plane retardation Re.sub.1=(nx.sub.1-ny.sub.1).times.d.sub.1 is 200 through 350 nm, where, a direction of the retardation film in which an in-plane refractive index within the film surface concerned gives a maximum is defined as X-axis, a direction perpendicular to X axis is defined as Y-axis, a thickness direction of the film is defined as Z-axis, refractive indexes in axial direction are defined as nx.sub.1, ny.sub.1, nz.sub.1, respectively, and a thickness of the film is defined as d.sub.1 (nm), and the transparent protective films comprise a thermoplastic saturated norbornene resin, may realize an easily viewable display with high contrast ratio in a wide range when applied to a display system and that may provide a retardation value stabilized under conditions of high temperature or high humidity.