An optical unit is provided which includes inorganic polarizing plates used as output polarizing plates. Even if a defect such as a flaw or a pinhole is present in the polarizing plate, the defect is not projected on the display screen. Instead of output polarizing plates for liquid crystal panels for R, G, and B, a common polarizing plate for R, G, and B is disposed on the output side of a photosynthesis prism. A color selective polarization rotator which rotates the polarization of light of a selected wavelength band is disposed between the photosynthesis prism and the common polarizing plate. Or, alternatively, instead of output polarizing plates for R and G to be individually disposed along with an output polarizing plate for B, a common output polarizing plate for R and G is disposed on the output side of the photosynthesis prism.