A semiconductor device includes a semiconductor structure including a first conductive semiconductor layer, a second conductive semiconductor layer, and an active layer provided between the first conductive semiconductor layer and the second conductive semiconductor layer, and a semiconductor device package including the semiconductor device. The active layer includes a plurality of barrier layers and a plurality of well layers. The second conductive semiconductor layer includes a conductive second semiconductor layer and a conductive first semiconductor layer provided on the conductive second semiconductor layer. The conductive second semiconductor layer has a higher aluminum composition than the well layers, and the conductive first semiconductor layer has a lower aluminum composition than the well layers.