A dispersion element includes a prism having a first transmission surface and an oppositely disposed second transmission surface, and an optical element having a third transmission surface and an oppositely disposed diffraction optical surface on which a diffraction grating is arranged. The prism and the optical element are integrated into one body by cementing the first transmission surface to the third transmission surface. The third transmission surface and the diffraction optical surface are non-parallel to each other in a plane perpendicular to grooves of the diffraction grating.