Exemplary embodiments of the present invention disclose a light-emitting device including a first power source connection terminal and a second power source connection terminal, the first and second power source connection terminals configured to be connected to an external power source, and a plurality of light emitting cell arrays, each of the plurality of light emitting cell arrays being connected in parallel to one another between the first and the second power source connection terminals, each of the plurality of light emitting cell arrays comprising serially connected light emitting cells. Each of the light emitting cells includes a first conductivity-type semiconductor layer, a second conductivity-type semiconductor layer, an active layer disposed between the first conductivity-type semiconductor layer and the second conductivity-type semiconductor layer, and an electrode pad disposed on the second conductivity-type semiconductor layer.