An optical film obtained by stretching a polymer film comprising a polycarbonate resin and a styrene resin: wherein a photoelastic coefficient is 2.0.times.10.sup.-11 to 6.0.times.10.sup.-11 m.sup.2/N, and a three dimensional refractive index is controlled so that an Nz coefficient may satisfy a relationship of Nz.ltoreq.0.9 and a front retardation (Re) may satisfy a relationship of Re.gtoreq.80 nm, has characteristics of giving wide viewing angle and also outstanding durability.