A projector includes an illumination device having a light source device emitting light, and a polarization conversion element adapted to emit light from the light source device as polarized light, a light modulation device adapted to modulate the light from the illumination device in accordance with image information, and a projection optical system adapted to project the light from the light modulation device, and the illumination device further includes a light diffusing unit disposed in at least one of upstream and downstream of the polarization conversion element.