The nitride-based semiconductor light-emitting device and manufacturing method thereof are disclosed: the nitride-based semiconductor light-emitting device includes a reflective layer formed on a support substrate, a p-type nitride-based semiconductor layer, a light-emitting layer and an n-type nitride-based semiconductor layer successively formed on the reflective layer, wherein irregularities are formed on a light extracting surface located above the n-type nitride-based semiconductor layer.