An illuminating device in which luminance unevenness caused by a lamp holder of a tubular
light source is reduced is provided as a large-area, thin illuminating device formed as a surface-emitting
light source by an edge light method, and a thin, large-screen
display device with low
power consumption that is able to obtain a display
image quality that is not a problem on a practical level is provided, by using the illuminating device as a backlight of a display element that displays an image by controlling transmission of light. The illuminating device includes a tabular
light guide including a light emitting surface that is preferably substantially rectangular, tubular light sources provided respectively opposite two opposing lateral surfaces of the
light guide, and at least one pair of lamp holders respectively holding the tubular light sources at intermediate portions of two opposing lateral surfaces of the
light guide, and the lamp holders in the pair are disposed so as to be displaced from each other in a tube axis direction of the tubular light sources.