A semiconductor light-emitting device includes a substrate, a first reflective layer disposed on the substrate and including first openings, a first conductivity-type semiconductor layer grown in and extending from the first openings and connected on the first reflective layer, a second reflective layer disposed on the first conductivity-type semiconductor layer and including second openings having lower surfaces disposed to be spaced apart from upper surfaces of the first openings, and a plurality of light-emitting nanostructures including nanocores extending from the second openings and formed of a first conductivity-type semiconductor material, and active layers and second conductivity-type semiconductor layers sequentially disposed on the nanocores.