A diffractive optical element in which eclipse of rays at a grating side surface
of a diffraction grating can be reduced is disclosed. In a diffractive optical
element comprises a plurality of diffraction gratings made of different materials
are laminated, at least one of the plurality of diffraction gratings includes a
region in which the grating side surface inclines or a region in which edges thereof
are shifted with respect to the edge of another diffraction grating adjacent thereto.
The inclination or shift amount is different according to the positions thereof
in a surface of the diffractive optical element in accordance with the incident
angle or emergent angle of a specified ray such as a ray determined on the basis
of an average value, gravity value, maximum value and minimum value obtained from
the distribution of incident angle or emergent angle or the like, rays, etc.