PURPOSE: To reduce a cost and to make a polarized light separating angle relatively small by providing the front surface of a substrate which allows the transmission of light and has no optical anisotropy with optical thin films having a polarized light separating characteristic, thereby forming diffraction gratings.

CONSTITUTION: The polarized light separating element 10 has the substrate 11 which allows the transmission of light and has no optical anisotropy and the diffraction gratings 12 which are formed by providing the front surface of the glass substrate 11 with the multilayered optical thin films having the polarized light separating characteristic. Spacings 13 are formed between the respective diffraction gratings 12 extending in parallel with each other. The multilayered optical thin films are formed by successively laminating high- refractive index materials and low-refractive index materials, such as, for example, ZrO2 and SiO2 by vapor deposition, etc. The desired diffraction angle meeting the polarization components is obtd. and the polarized light sepn. of incident light is executed by selecting the pattern of the diffraction gratings 12 and the characteristic of the multilayered optical thin films.