According to one embodiment, an illumination device comprises a plurality of light emitting elements that are disposed on a main surface of a wiring board, a light diffusion distance maintaining layer, a wavelength conversion layer, and a prism sheet, wherein the main surface of the wiring board is divided into a plurality of segment regions, n (n>1) light emitting elements are provided in each of the segment regions, the light emitting elements are independently driven in units of the segment regions, and a thickness of the light diffusion distance maintaining layer is ½ times or more a pitch of the segment regions adjacent to each other.