An optical element of the present invention is constituted by a multilayer structure having a polarizing plate, and a light diffusing plate. The light diffusing plate is formed of a birefringent film containing dispersed therein minute regions differing from the birefringent film in birefringent characteristics. The minute regions are formed of a thermoplastic liquid-crystal polymer. The difference in refractive index between the birefringent film and the minute regions in a direction perpendicular to the axis direction in which a linearly polarized light has a maximum transmittance, n¹, is 0.03 or larger and that in said axis direction, n², is not larger than 80% of the n¹. Furthermore, the n¹ direction for the light diffusing plate is parallel to the transmission axis of the polarizing plate. A liquid-crystal display of the present invention has a liquid-crystal cell and the optical element disposed on one or each side of the cell.