A semiconductor light emitting device includes a first conductivity-type semiconductor layer, an active layer and a second conductivity-type semiconductor layer sequentially stacked on a substrate. A first electrode is disposed on a portion of the first conductivity-type semiconductor layer. A current diffusion layer is disposed on the second conductivity-type semiconductor layer and includes an opening exposing a portion of the second conductivity-type semiconductor layer. A second electrode covers a portion of the current diffusion layer and the exposed portion of the second conductivity-type semiconductor layer, wherein the portion of the current diffusion layer is near the opening.