PURPOSE: To improve picture quality on a screen, in enlargingly projecting a color image light beam through color synthesis with a dichroic mirror, by arranging the dichroic mirror for which a dichroic film is formed on the surface of a wedge-shaped glass material, for only the number corresponding to the plural color image light beams, and thereby preventing the color slurring of the dichroic mirror.

CONSTITUTION: Plural light beams of a prescribed color are optically modulated by a light space modulator 2R, 2G, 2B, with the resultant plural color image light beams synthesized by a hue synthesizer 10R, 10G, 10B and projected through a projection lens 11. In this projector device 1, the hue synthesizer 10G, 10B is structured such that a dichroic mirror is arranged in the number corresponding to the plural color image light beams, a dichroic mirror with a dichroic film formed on the surface of a wedge-shaped glass material in which the incident plane and the light-emitting plane are nonparallel and in which a space narrows between the two planes in proximity to the incident light axis on the transmitting light side. As a result, the wedge shape prevents the color slurring, improving picture quality on the screen.