One aspect of the present invention provides a method for manufacturing a nanostructure semiconductor light emitting device comprising the steps of: providing a base layer formed of a first conductive semiconductor; forming a mask including an etch stop layer on the base layer; forming a plurality of openings exposing areas of the base layer on the mask; forming a plurality of nano cores by growing the first conductive semiconductor on the exposed areas of the base layer so as to fill the plurality of openings; partially removing the mask by using the etch stop layer so as to expose sides of the plurality of nano cores; and sequentially growing an active layer and a second conductive semiconductor on surfaces of the plurality of nano cores.