To provide an illumination optical apparatus which does not spoil the uniformity of an illumination distribution and which can correct telecentricity.

An illumination optical apparatus is provided with secondary- light-source formation means 1, 2 which form a secondary light source on the basis of a luminous flux from a light source, with a multiple-light-source-image formation means 32 which forms many light-source images on the basis of a luminous flux from the secondary light source, with condenser optical systems 34, 35 which condense luminous fluxes from the many light-source images and by which a face R to be irradiated is illuminated telecentrically and with a relay optical system 31 by which the position of the secondary light source and positions of the many light-source images are conjugated. Then, the secondary light source, the relay optical system and the multiple-light-source-image formation means can be moved integrally.