A three-dimensional image display device comprising: a display panel which displays left eye and right eye images; and a backlight unit which supplies light to the display panel, wherein the backlight unit comprises a light guide part comprising first and second light guide units (310, 320), wherein each of the light guide units (310, 320) comprises: a light guide plate (311, 321) comprising a light emission surface through which supplied light is emitted, a bottom surface which faces the light emission surface, and side surfaces which connect the light emission surface to the bottom surface; a plurality of light sources (312, 322) which emit light toward at least one of the side surfaces; and a band pass filter (313, 323) between the side surface to which the light is emitted and the light sources, wherein the band pass filter (313, 323) comprises a plurality of filter units each including a plurality of films which are stacked and have refractive indexes different from each other, and wherein the filter units of the band pass filter included in the first light guide unit and the filter units of the band pass filter included in the second light guide unit have constitutions different from each other, so the filter units of the band pass filter included in the first light guide unit reflect light having wavelengths different from the filter units of the band pass filter included in the second light guide unit. a display panel which displays left eye and right eye images; and a backlight unit which supplies light to the display panel, wherein the backlight unit comprises a light guide part comprising first and second light guide units (310, 320), wherein each of the light guide units (310, 320) comprises: a light guide plate (311, 321) comprising a light emission surface through which supplied light is emitted, a bottom surface which faces the light emission surface, and side surfaces which connect the light emission surface to the bottom surface; a plurality of light sources (312, 322) which emit light toward at least one of the side surfaces; and a band pass filter (313, 323) between the side surface to which the light is emitted and the light sources, wherein the band pass filter (313, 323) comprises a plurality of filter units each including a plurality of films which are stacked and have refractive indexes different from each other, and wherein the filter units of the band pass filter included in the first light guide unit and the filter units of the band pass filter included in the second light guide unit have constitutions different from each other, so the filter units of the band pass filter included in the first light guide unit reflect light having wavelengths different from the filter units of the band pass filter included in the second light guide unit. a light guide plate (311, 321) comprising a light emission surface through which supplied light is emitted, a bottom surface which faces the light emission surface, and side surfaces which connect the light emission surface to the bottom surface; a plurality of light sources (312, 322) which emit light toward at least one of the side surfaces; and a band pass filter (313, 323) between the side surface to which the light is emitted and the light sources, wherein the band pass filter (313, 323) comprises a plurality of filter units each including a plurality of films which are stacked and have refractive indexes different from each other, and wherein the filter units of the band pass filter included in the first light guide unit and the filter units of the band pass filter included in the second light guide unit have constitutions different from each other, so the filter units of the band pass filter included in the first light guide unit reflect light having wavelengths different from the filter units of the band pass filter included in the second light guide unit.