To provide a compact illuminator and a liquid crystal projector constituted so that the synthesized part of an optical path may be small without causing the loss of light quantity and having high light utilization efficiency.

Illuminating light beams from light sources (1a and 2a) are condensed by reflectors (1b and 2b), reflected and synthesized by a synthesizing mirror (3) so that optical paths may be superposed, and made parallel beams or nearly parallel beams by a collimator lens(CL), then the spatial energy distribution thereof is uniformized by an integrator optical system consisting of 1st and 2nd lens arrays (4 and 5) and the like. The collimator lens(CL) has telephoto type power arrangement consisting of a positive lens (G1) and a negative lens (G2), and its principal point is positioned on the outside of the collimator lens(CL).