In a three-dimensional image display device for displaying color three-dimensional images, a fly eye lens, a display panel, and a light source are provided in this order from the observer side. A display panel has four pixels arrayed in a (2×2) matrix correlated with one lens element of the fly eye lens. In the event that j is a natural number, a pixel magnifying projection width e in a second direction is set in a range of the following expression according to mean interpupillary distance Y of the observers. e 3 ≠ Y 2 × j