The present invention provides an organic light emitting device comprising a substrate, a first electrode, an organic material layer and a second electrode in sequentially laminated form, wherein a plurality of continued hemispherical recesses are formed on an upper surface of the substrate aligned adjacent to the first electrode. In addition, The present invention provides a method comprising the steps of a) dipping a substrate having at least one aluminum surface in an acid solution, and applying oxidation voltage of 10 to 400 V to the substrate so as to form an aluminum oxide layer on the aluminum surface of the substrate in such a manner that a plurality of continued recesses are formed on the aluminum oxide layer, and a plurality of continued recesses having curvature in identical direction to that of the recesses on the aluminum oxide layer are formed on an interface between the aluminum oxide layer and the substrate; b) removing the aluminum oxide layer from the substrate, thereby forming a plurality of continued hemispherical recesses; and c) forming an organic material layer and an electrode on one surface of the substrate formed with the hemispherical recesses.