A vertical group III-nitride light emitting device and a manufacturing method thereof are provided. The light emitting device comprises: a conductive substrate; a p-type clad layer stacked on the conductive substrate; an active layer stacked on the p-type clad layer; an n-doped AlxGayIn1-x-yN layer stacked on the active layer; an undoped GaN layer stacked on the n-doped layer; and an n-electrode formed on the undoped GaN layer. The undoped GaN layer has a rough pattern formed on a top surface thereof.