An optical element in which the light transmittance decreases monotonously from the central part toward the peripheral part, characterized in that: the element comprises both an absorbing material section which is made of a material that can absorb a part of light and the thickness of which increases monotonously from the central part toward the peripheral part and a transparent material section which is made of a light-transmitting material and which is laminated on the absorbing material section; and the refractive index of the absorbing material section is different from that of the transparent material section.