A retardation film of the present invention comprises 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.ltoreq.(nx-ny)d.ltoreq.350 nm, (1)
0.1.ltoreq.(nx-nz)/(nx-ny).ltoreq.0.9, (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. The retardation film is hard
to cause a shift or an unevenness of a retardation value due to a stress.