OPTICAL ELEMENT, MOLD AND OPTICAL DEVICE

PROBLEM TO BE SOLVED: To provide an optical element that has high anti-reflection effect.SOLUTION: An optical element 1 is formed of a transparent material that has a predetermined refractive index corresponding to light of a use wavelength area, and has a cone-like fine structure formed on at least one surface of a light incident surface of the optical element 1 and a light emergent surface thereof. The fine structure has a first structure s21 serving as a protrusion section in which an average height H1 satisfies a condition of H1≤1/3*λ/n and a second structure s22 serving as a cavity section in which an average height H2 satisfies a condition of H2≤1/3*λ/n, and an average distance P between fine structures satisfies H1/2≤P≤1/3*λ/n and H2/2≤P≤1/3*λ/n, where a use wavelength is λ, and a refractive index corresponding to the use wavelength is n.