An illumination device is provided that reduces the amount of light leaked to improves illumination efficiency. Electroluminescent elements are formed on one surface of a transparent substrate. The electroluminescent elements are provided with at least a transparent electrode, a light emitting layer, and a reflective electrode in order from the outgoing surface of the transparent substrate. Concavities are formed on one surface of the transparent substrate and the reflective electrode is formed in the concavities. Alternatively, electroluminescent elements are arranged in a planar configuration, and the intervals between the electroluminescent elements and the intervals between the pixels are set so as not to be equal to each other. Also, the directions in which the electroluminescent elements extend and the directions in which the pixels are aligned are set so as not to be parallel to each other.