A semiconductor light emitting device includes a substrate having a first major surface and a second major surface, a semiconductor layer that includes a first semiconductor layer of a first conductive type formed on the first major surface of the substrate, a light emitting layer formed on the first semiconductor layer and a second semiconductor layer of a second conductive type formed on the light emitting layer, and a mesa structure formed in the semiconductor layer by selectively notching the first semiconductor layer, the light emitting layer and the second semiconductor layer so as to expose the first semiconductor layer, and a ratio of a luminescent area of the light emitting Layer with respect to an area of the first major surface of the substrate being set to equal to or smaller than 0.25.