To obtain an illumination optical system which can form a pupil intensity distribution of desired shape and illuminance, and can achieve illumination conditions rich in diversity.

The illumination optical system used in an exposure device for exposing a substrate with light from a pattern, distributing the illumination light from a light source to the pupil surface and illuminating a pattern with the illumination light passed through the pupil surface includes first light modulators placed two-dimensionally on the optical path of illumination light, each having a plurality of optical elements subjected to attitude control individually and modulating an incident light beam to a light beam having a predetermined angular distribution, second light modulators imparting an angular distribution to the illumination light passed through the first light modulators, and relay optical systems interposed between the first light modulators and second light modulators. The pattern is illuminated with the illumination light passed through the second light modulators.