In a semiconductor light emitting device, a light emitting structure includes a first-conductivity type semiconductor layer, an active layer, and a second-conductivity type semiconductor layer, which are sequentially formed on a conductive substrate. A second-conductivity type electrode includes a conductive via and an electrical connection part. The conductive via passes through the first-conductivity type semiconductor layer and the active layer, and is connected to the inside of the second-conductivity type semiconductor layer. The electrical connection part extends from the conductive via and is exposed to the outside of the light emitting structure. An insulator electrically separates the second-conductivity type electrode from the conductive substrate, the first-conductivity type semiconductor layer, and the active layer. A passivation layer is formed to cover at least a side surface of the active layer in the light emitting structure. An uneven structure is formed on a path of light emitted from the active layer.