A projection display device has an illumination optical system that includes a light-intensity equalization element, a first optical system, and an aperture regulation member. The aperture regulation member is disposed at a position that is not optically conjugate with the screen, and the aperture regulation member has at least one of the following, using measured or calculated relative illuminances at each of multiple segments of the image formation region or screen: an aperture expansion part provided at a position corresponding to a segment with a low relative illuminance, the aperture expansion part being a cutout that narrows the light-blocking section and widens the aperture section; an aperture contraction part provided at a position corresponding to a segment with a high relative illuminance, the aperture contraction part being a protrusion that widens the light-blocking section and narrows the aperture section.