An image display device includes: at least one illumination system adapted to emit a light beam; at least one light modulation element adapted to modulate the light beam emitted from the illumination system; and a projection optical system adapted to project the light beam modulated by the light modulation element, wherein a proceeding direction of a principal ray of the light beam modulated by the light modulation element is nonparallel to an optical axis of the projection optical system when the light beam modulated by the light modulation element enters the projection optical system.