Disclosed herein is a light emitting device including a light emitting structure including a first conductivity-type semiconductor layer, a second conductivity-type semiconductor layer, and an active layer including at least one combination of a well layer of a first composition formed of a nitride-semiconductor material having first electronic energy and a barrier layer of a second composition formed of a nitride-semiconductor material having higher electronic energy than the first electronic energy, and an interface layer disposed between the second conductivity-type semiconductor layer and the active layer or between the first conductivity-type semiconductor layer and the active layer. The interface layer includes first, second and third layers having different energy bandgaps, the energy bandgaps of the first and second layers are greater than the energy bandgap of the barrier layer, and the energy bandgap of the third layer is less than the energy bandgap of the barrier layer.