Patent ID: 7336857

Claim:
A retardation film comprising a stretched film of a polymer film containing a norbornene-based resin, wherein the stretched film satisfies the following equation (1) and the equation (2); 100 nm≦( nx−ny ) d ≦350 nm (1) 0.45<( nx−nz )/( nx−ny )≦0.6 (2) where the refractive indices in the slow axis direction, the fast axis direction and the thickness direction of the film are nx, ny and nz, respectively, d(nm) is thickness of the film, and the slow axis direction is a direction that the refractive index in film plane is maximum, wherein an absolute value of photoelastic coefficient of the retardation film at 23° C. is from 1.0×10 −12 m 2 /N to 12.0×10 −12 m 2 /N.