Abstract: A prism sheet is provided for making it possible to ensure high brightness and a wide viewing angle characteristic in a state integrated with a reflective polarizing function film. A prism sheet (7) is composed of a plurality of lens units (7a) which each have substantially triangle shapes in cross-section and extend along their ridgelines and are formed in parallel at least on a surface. The prism has such a structure that it is put between a pair of polarizers disposed in a cross Nicol arrangement to make its ridge line consistent with a transmission axis of either of the polarizers. The total transmittance of light beams incident from the external surface on the shape arrangement side of such structured prism sheet (7) is not larger than 2% of the total transmittance of light beams through such a parallel Nicol structure of a pair of polarizers that no prim sheet is put between them.