A method of manufacturing a nanostructure semiconductor light emitting device may includes preparing a mask layer by sequentially forming a first insulating layer and a second insulating layer on a base layer configured of a first conductivity-type semiconductor, forming a plurality of openings penetrating the mask layer, growing a plurality of nanorods in the plurality of openings, removing the second insulating layer, preparing a plurality of nanocores by re-growing the plurality of nanorods, and forming nanoscale light emitting structures by sequentially growing an active layer and a second conductivity-type semiconductor layer on surfaces of the plurality of nanocores. The plurality of openings may respectively include a mold region located in the second insulating layer, and the mold region includes at least one curved portion of which an inclination of a side surface varies according to proximity to the first insulating layer.