A projection display device having a projection device projecting an image on a surface, and a position detection function of detecting an object's position between the surface and the projection device, includes: a light source emitting light beams toward the object; a light detector detecting the light beams reflected by the object; and a position detector detecting the object's position in an imaginary plane based on the light detector's result, wherein the light source emits, as the light beams, first through third light beams having first through third intensity distributions, the second intensity distribution having a highest intensity at a position failing to overlap a highest intensity of the first intensity distribution, and the third intensity distribution having a highest intensity portion at a position failing to overlap a straight line connecting the highest intensity portions of the first and second intensity distributions.