Disclosed are a light emitting device, a light emitting device package, and an illumination system. The light emitting device includes a substrate; a light emitting structure layer including a first conductive type semiconductor layer formed on the substrate and having first and second upper surfaces, in which the second upper surface is closer to the substrate than the first upper surface, an active layer on the first conductive type semiconductor layer, and a second conductive type semiconductor layer on the active layer; a second electrode on the second conductive type semiconductor layer; and at least one first electrode extending at least from the second upper surface of the first conductive type semiconductor layer to a lower surface of the substrate by passing through the substrate.