An illumination optical apparatus for illuminating a pattern on a mask with illumination light through a pupil plane of the illumination optical apparatus, the illumination optical apparatus comprising: an optical integrator arranged in an optical path of the illumination light; the apparatus being characterised by: a plurality of birefringent members (12,13) arranged in the optical path on an incidence side of the optical integrator to change a polarization state of the illumination light; and an optical member (41,42) arranged in the optical path between the plurality of birefringent members and the optical integrator and being configured to change a light quantity distribution of the illumination light on the pupil plane, in which a light quantity of a first region is larger than that of a second region, the first region being away from an optical axis of the illumination optical apparatus, the second region including the optical axis, wherein a direction of a fast axis of at least one birefringent member out of the plurality of birefringent members is different from a direction of a fast axis of another birefringent member out of the plurality of birefringent members, and wherein the plurality of birefringent members provides different thicknesses of birefringent material for beams incident thereto at different incidence positions such that, when the illumination light enters the plurality of birefringent members in a substantially single polarization state, a polarization direction of the illumination light in the first region on the pupil plane is substantially coincident with a circumferential direction about the optical axis so as to illuminate the pattern with the illumination light in a polarization state in which a principal component is S-polarized light. an optical integrator arranged in an optical path of the illumination light; the apparatus being characterised by: a plurality of birefringent members (12,13) arranged in the optical path on an incidence side of the optical integrator to change a polarization state of the illumination light; and an optical member (41,42) arranged in the optical path between the plurality of birefringent members and the optical integrator and being configured to change a light quantity distribution of the illumination light on the pupil plane, in which a light quantity of a first region is larger than that of a second region, the first region being away from an optical axis of the illumination optical apparatus, the second region including the optical axis, a plurality of birefringent members (12,13) arranged in the optical path on an incidence side of the optical integrator to change a polarization state of the illumination light; and an optical member (41,42) arranged in the optical path between the plurality of birefringent members and the optical integrator and being configured to change a light quantity distribution of the illumination light on the pupil plane, in which a light quantity of a first region is larger than that of a second region, the first region being away from an optical axis of the illumination optical apparatus, the second region including the optical axis, wherein a direction of a fast axis of at least one birefringent member out of the plurality of birefringent members is different from a direction of a fast axis of another birefringent member out of the plurality of birefringent members, and wherein the plurality of birefringent members provides different thicknesses of birefringent material for beams incident thereto at different incidence positions such that, when the illumination light enters the plurality of birefringent members in a substantially single polarization state, a polarization direction of the illumination light in the first region on the pupil plane is substantially coincident with a circumferential direction about the optical axis so as to illuminate the pattern with the illumination light in a polarization state in which a principal component is S-polarized light.