The present invention relates to an optical film comprising: a blended resin including 1) an acrylic copolymer resin containing an alkyl methacrylate monomer and a (metha) acrylic monomer containing an alicyclic or an aromatic ring, 2) a copolymer resin containing an alkyl methacrylate monomer, an aromatic vinyl monomer, and an acid anhydride monomer, and 3) a resin containing an aromatic or an alicyclic ring in the main chain of a polymer. The present invention also relates to a method for manufacturing the optical film, and a liquid crystal display device comprising the optical film. The optical film according to the present invention is excellent in heat resistance, optical transparency, mechanical strength, durability, and the like.