An illumination optical apparatus includes a plurality of birefringent members made of a birefringent material and arranged in an optical path on an incidence side of an optical integrator. The members change a polarization state of illumination light such that first and second rays of the illumination light are polarized in different directions on the pupil plane. The birefringent members are arranged such that an optical path length of the first ray in the birefringent material is different from an optical path length of the second ray in the birefringent material, and are arranged so as to change the polarization state of the illumination light incident on the plurality of the birefringent members in a linear polarization state having a substantially single polarization direction such that each of the first and second rays is polarized in a substantially circumferential direction about the optical axis on the pupil plane.