An illumination apparatus includes a red light valve, a green light valve, a blue light valve, a polarization adjustment element, and a color combiner. The polarization adjustment element adjusts polarization of fourth color component light. The color combiner combines light emitted from the red light valve, the green light valve and the blue light valve. Superimposed component light which is any one of a red component light, a green component light and a blue component light enters the polarization adjustment element together with a fourth color component light. The polarization adjustment element transmits the superimposed component light without adjusting the polarization, and transmits the fourth color component light with adjusting the polarization. The superimposed component light and the fourth color component light emitted from the polarization adjustment element enter a specific light valve corresponding to the superimposed component light, among the red light valve, the green light valve and the blue light valve.