ILLUMINATION DEVICE AND PROJECTOR

PROBLEM TO BE SOLVED: To lessen the illumination unevenness of an illumination device and to reduce its size. SOLUTION: The parallel luminous fluxes emitted from a light source 11 are made incident on an illumination plate 12. This illumination plate 12 is formed by lining up a plurality of tile-like wedge plates 12a longitudinally and transversely on a plane orthogonal with the progression direction of the light. The external shape when the wedge plates 12a are viewed from the side of a light valve 13 nearly coincides with the shape of the portion to be illuminated of the light valve 13. The plural wedge plates 12a have different vertex angles. The vertex angle of the wedge plates 12a existing around the circumference of the illumination plate 12 is larger than the vertex angle existing at the center. The parallel luminous fluxes emitted from the light source 1 are split to the plural small luminous fluxes while the parallel state of the luminous fluxes is maintained when passing each of the plural wedge plates 12a. These plural small luminous fluxes are so introduced as to illuminate the same portion to be illuminated of the light valve 13 in superposition, by which the luminance unevenness of the light source 11 is averaged and the uniform illuminance may be obtained on the light valve 13.