PURPOSE: To provide the antireflection film having an excellent transmission characteristic and an effect of preventing ghosts and flares to an optical system formed by using a CCD as a solid state image pickup element.

CONSTITUTION: The antireflection film 1 of a four-layered constitution to be disposed on the surface of the optical element 2 for forming images on the color image pickup element arranged with band-pass filters of three colors R, G, B is assumed to be composed of the first layer, second layer, third layer and fourth layer successively from the optical element surface side. If the refractive indices of the respective layers are defined successively as n1 to n4 and if the refractive index of the optical element is defined as n0, n2 is nearest n0 as compared with others and the refractive indices have relations n1, n4<n0<n3. If the prescribed wavelength is defined as λ0, the optical thicknesses D1 to D4 expressed by the products of the thicknesses of the respective layers and the refractive indices are Di=0.375 to 0.575λ0, D2=0.125 to 0.250λ0, D3=0.435 to 0.700λ0, D4=0.215 to 0.350λ0.