A light emitting device, a method of manufacturing the same, a light emitting device package, and a lighting system are disclosed. The light emitting device may include a first conductive semiconductor layer, a second conductive semiconductor layer, and an active layer interposed between the first and second conductive semiconductor layers. The first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer may include Al. The second conductive semiconductor layer may have Al content higher than Al content of the first conductive semiconductor layer. The first conductive semiconductor layer may have Al content higher than Al content of the active layer.