a projection image display device includes a rod lens of rectangular cross section , into which white light from a light source enters , and exits as diffused light of uniform illumination intensity . the rod lens is provided with : only a single pair of rods which are formed by splitting the rod lens along the optical axis so as to bifurcate it along long sides of the rectangular cross section , and which have a thin filmed formed on a portion at the periphery of the mutually opposed surfaces thereof ; and with a cover part that covers the outside periphery of the pair of rods , for retaining the pair of rods in such a way that the rods are opposed a slight distance apart due to the thin film formed on the mutually opposed surfaces , and that has openings formed at the light entry side and the light exit side of the rod lens .