| abstract |
A retardation film capable of suppressing a change in retardation when tilted in the Z-axis direction is provided. The retardation element has an in-plane retardation R0 and a thickness direction retardation Rth of 0.7 × R0 ≦ Rth ≦ 1.3 × R0 (R0: | Nx−Ny | × d, Rth: | ((Nx + Ny ) / 2) −Nz | × d, Nx: refractive index in the width direction, Ny: refractive index in the length direction, Nz: refractive index in the thickness direction, d: element thickness). [Selection] Figure 1 |