The invention provides a light emitting device comprising a mark body, a substrate arranged in back of the mark body, an LED mounted on an opposite surface of the substrate to the mark body, and a light guide arranged on a closer side of the substrate to the LED and having an upper surface serving as a light introducing surface for introducing LED-based light, a side surface serving as a light emitting surface and a backside subjected to a light diffuse reflection process to cause diffuse reflection by the backside. Incidentally, there can be provided a light emitting device comprising a light guide arranged on a closer side of the substrate to the LED and having an upper surface serving as a light introducing surface for introducing LED-based light, a side surface serving as a light emitting surface and a backside having a plurality of protrusions in a rib form.