Reflection-type polarized light separation diffraction element and optical measurement device provided with same

*The invention provides a reflection-type polarization separation diffraction element which can be used in a wide wavelength range including an ultraviolet region, and an optical measurement device provided with the same. A reflective polarization splitting diffraction element is provided with: a substrate (1); a reflecting surface (2) formed on the surface of the substrate (1); and a grating-shaped structure (3) that is provided on the reflecting surface (2) and exhibits structural birefringence ([delta] n *). The grating-shaped structure (3) is configured from grating-shaped structures (3A, 3B, 3C, and 3D) of four patterns, and the grating-shaped structures of the four patterns have grating-shaped structures having different azimuth angles from each other. The plurality of patterns of grating-shaped structures (3A, 3B, 3C, 3D) are arranged in a predetermined direction on the reflective surface (2) so that the azimuth angles of the grating-shaped structures change in structural periodicity. 本发明提供一种能够在包括紫外区的宽