A method of fabricating a light emitting device comprising: forming a plurality of nano structures on a substrate by forming a protective film on the substrate; forming a thin film layer including a metal on the protective film; thermal-processing the thin film layer including the metal to form a plurality of nano agglomerations on the protective film; etching the protective film using the plurality of nano agglomerations as a mask; removing the plurality of nano agglomerations; etching a top surface of the substrate using the etched protective film as a mask to thereby form the plurality of nano structures on the substrate; and removing the protective film, forming on the plurality of nano structures a light emitting structure including a first semiconductor layer having a first polarity, an active layer on one surface of the first semiconductor layer and a second semiconductor layer having a polarity opposite that of the first semiconductor layer; forming a support on the light emitting structure; removing the substrate from the light emitting structure; removing the support; forming a first electrode on the surface of the first semiconductor layer, which faces away from the active layer; forming a second electrode on the second semiconductor layer, the second electrode including a reflective ohmic electrode and a metal layer, the reflective ohmic electrode being formed on an entire area of the surface of the second semiconductor layer, which faces away from the active layer; and forming a support on the metal layer configured to support the metal layer, wherein each width of the plurality of nano agglomerations is within a range of 10 nm to 2000 nm. forming a plurality of nano structures on a substrate by forming a protective film on the substrate; forming a thin film layer including a metal on the protective film; thermal-processing the thin film layer including the metal to form a plurality of nano agglomerations on the protective film; etching the protective film using the plurality of nano agglomerations as a mask; removing the plurality of nano agglomerations; etching a top surface of the substrate using the etched protective film as a mask to thereby form the plurality of nano structures on the substrate; and removing the protective film, forming on the plurality of nano structures a light emitting structure including a first semiconductor layer having a first polarity, an active layer on one surface of the first semiconductor layer and a second semiconductor layer having a polarity opposite that of the first semiconductor layer; forming a support on the light emitting structure; removing the substrate from the light emitting structure; removing the support; forming a first electrode on the surface of the first semiconductor layer, which faces away from the active layer; forming a second electrode on the second semiconductor layer, the second electrode including a reflective ohmic electrode and a metal layer, the reflective ohmic electrode being formed on an entire area of the surface of the second semiconductor layer, which faces away from the active layer; and forming a support on the metal layer configured to support the metal layer, wherein each width of the plurality of nano agglomerations is within a range of 10 nm to 2000 nm.