A projection display device which displays an image by projecting the image on a screen includes a laser light source 1 (1a, 1b, 1c) for emitting coherent light, a display device 3 for forming an image to be displayed on a screen 5 in an area illuminated by a luminous flux from the laser light source 1, a first diffusion plate 14 for diffusing a luminous flux, and a second diffusion plate 15 for diffusing a luminous flux. The first diffusion plate 14 is provided in at least one of a conjugate position of the laser light source 1 or the vicinity of the conjugate position in the optical path of the optical system including the laser light source 1 through the screen 5. The second diffusion plate 15 is provided in at least one of a conjugate position of the display device 3 or the vicinity of the conjugate position. At least one of the first diffusion plate 14 and the second diffusion plate 15 fluctuates perpendicularly to an optical axis.