This projection display device includes: a light source unit emitting a white light along a first optical axis; a lighting unit provided on a second optical axis, the lighting unit splitting the white light into predetermined color lights and uniformizing an illuminance distribution of the predetermined color lights; an image generator including a display element modulating the predetermined color lights, and a projection lens projecting an image light including the predetermined color lights modulated along a third optical axis; at least one optical path switching unit selectively switching between reflection and transmission of the white light; a light diffuser including a diffusion optical system spreading the white light to a desired illumination area and projecting the spread white light as an illumination light; and a controller causing the at least one optical path switching unit to switch between emission of the image light and emission of the illumination light.