A light emitting device including a first LED sub-unit having a thickness in a first direction, a second LED sub-unit disposed on a portion of the first LED sub-unit in the first direction, each of the first and second LED sub-units comprising a first-type semiconductor layer, a second-type semiconductor layer, and an active layer, a reflective electrode disposed adjacent to the first LED sub-unit and electrically connected to the first-type semiconductor layer of the first LED sub-unit, and a first ohmic electrode forming ohmic contact with the second-type semiconductor layer of the first LED sub-unit, in which the active layer of the first LED sub-unit is configured to generate light, includes AlxGa(1-x-y)InyP (0≤x≤1, 0≤y≤1), and overlaps the active layer of the second LED sub-unit in the first direction, and the active layer of the second LED sub-unit includes the same material as the active layer of the first LED sub-unit.