An illumination apparatus includes: a first dichroic mirror; a second dichroic mirror which separates the combined light into a red component light R and the green component light G; and a polarization adjuster provided on an optical path of the combined light between the dichroic mirrors. The polarization adjuster adjusts a polarization direction of a yellow component light Ye in the combined light. A second dichroic mirror separates the combined light into the red component light R on which a part of or all of the yellow component light Ye is superimposed and the green component light G on which the rest of the yellow component light Ye is superimposed.