Provided is an illuminating device including a plurality of light sources. Micro prisms are provided in an opposed surface of a light guide plate. Each of the micro prisms is provided so that a reflective surface has a bottom side located at substantially 90 degrees with respect to an optical path of a beam from any one of the light sources. In a display device including a liquid crystal panel illuminated by the illuminating device, at least two micro prisms are provided in each area overlapped with aperture portions of the liquid crystal panel.