To reduce uneven illumination and facilitate projection exposure onto a large screen with high resolution by providing two optical integrators having a refractive force in a predetermined direction at a part of an illumination system in such a manner, that the optical integrators may be driven in a scanning direction and in a scanning orthogonal direction which is orthogonal to the scanning direction.

Illuminance uniforming means 6 has a first optical integrator 20, and a second optical integrator 22 which is constituted by an aggregate of lens elements, having a refractive force on a scanning orthogonal cross section orthogonal to a scanning direction. The scanning direction (X-direction) is a first direction, and the scanning orthogonal direction (Y-direction) orthogonal to the scanning direction is a second direction. A luminous flux incident on a plane of incidence 20a of the first optical integrator 20 becomes incident on the second integrator 22. Then, a plurality of secondary light sources are formed on an exit plane 22b of the second integrator 22.