An optical element including a first layer (011) made of a medium having optical anisotropy, wherein a difference between refractive indexes nh and nl (nh>nl) at a central wavelength λ for first and second polarized lights which enter the optical element and whose polarization directions are different from each other is at least 0.1, and wherein conditions (nt1−nl)·(nl−nt2)≦0 and nt1