Abstract: An organic light emitting device enables improvement on the loss of optical extraction efficiency due to total reflection and optical waveguide effects. The organic light emitting device has a structure wherein a first electrode, an organic substance layer, and a second electrode are sequentially laminated on a substrate, a random nano structure having a fine pattern of a peaks-and-valleys shape is formed between a substrate and a first electrode to extract any light that is wasted due to total reflection and an optical waveguide mode to the outside of the substrate so that an organic light emitting device with improved external quantum efficiency can be realized, and optical extraction patterns and color changes due to visual field angles can also be improved.