A light emitting device according to an embodiment comprises a first conductive semiconductor layer; a second conductive semiconductor layer; and an active layer which is located between the first conductive semiconductor layer and the second conductive semiconductor layer and includes a plurality of barrier layers and a plurality of well layers that are located alternatively. The active layer includes a first region which is adjacent to the first conductive semiconductor layer and a second region which is located on the first region and is adjacent to the second conductive semiconductor layer, wherein the thickness of the well layer in the first region is thicker than the thickness of the well layer in the second region.
