A light emitting device and a method for fabricating the same are disclosed, whereby a thin mask film is changed to agglomerates by a simple thermal treatment process, and a plurality of nano openings, each opening spaced a distance apart, are formed in the agglomerates, a light emitting structure exposed to the nano openings is etched to form nano grooves and nano openings therein, enabling to enhance a light emitting area and to reduce the totally reflected light for an improvement of the light extraction efficiency.