A vertical structure non-volatile memory device in which a gate dielectric layer is prevented from protruding toward a substrate; a resistance of a ground selection line (GSL) electrode is reduced so that the non-volatile memory device is highly integrated and has improved reliability, and a method of manufacturing the same are provided. The method includes: sequentially forming a polysilicon layer and an insulating layer on a silicon substrate; forming a gate dielectric layer and a channel layer through the polysilicon layer and the insulating layer, the gate dielectric layer and the channel layer extending in a direction perpendicular to the silicon substrate; forming an opening for exposing the silicon substrate, through the insulating layer and the polysilicon layer; removing the polysilicon layer exposed through the opening, by using a halogen-containing reaction gas at a predetermined temperature; and filling a metallic layer in the space formed by removing the polysilicon layer.