A technique capable of easily manufacturing a projector without deteriorating too much the optical characteristics of the projector. A projector includes an illuminating optical system for emitting illumination light, an electro-optical device for modulating light from the illuminating optical system according to image information, and a projection optical system for projecting a modulated light beam flux obtained by the electro-optical device. The electro-optical device includes a single-crystal sapphire substrate having nearly a rectangular shape, and a polarizer provided on the single-crystal sapphire substrate on at least one side of a light incidence surface and a light emission surface. The single-crystal sapphire substrate includes a c-axis substantially parallel to the surface of the substrate, and the c-axis has an inclination of about 3° to about 7° with respect to a reference side selected from perpendicularly intersecting two sides of the nearly rectangular shape.