There is provided a nanostructure semiconductor light-emitting device including a base layer formed of a first conductivity-type semiconductor, an insulating layer disposed on the base layer and having a plurality of openings, and a plurality of light-emitting nanostructures disposed the plurality of openings, respectively. Each of light-emitting nanostructures includes a nanocore formed of a first conductivity-type semiconductor, and an active layer and a second conductivity-type semiconductor layer sequentially disposed on a surface of the nanocore. The plurality of light-emitting nanostructures are formed through the same growth process and divided into n groups (where n is an integer of two or more), each of which having at least two light-emitting nanostructures. At least one of a diameter, a height, and a pitch of the nanocores is different by group so that the active layers emit light having different wavelengths by group.