A method of manufacturing an organic light emitting device by which a pixel defining layer can be easily formed. The method includes: forming a first electrode on a substrate; forming a photoresist layer to cover the first electrode; patterning the photoresist layer and forming a blocking layer so that the blocking layer is on a side of the first electrode opposite to a side facing the substrate; forming a pixel defining layer on the substrate to cover side ends of the first electrode; removing the blocking layer and exposing the side of the first electrode contacting the blocking layer; forming an intermediate layer including an organic light emitting layer on the side of the first electrode that is exposed by removing the blocking layer; and forming a second electrode on the intermediate layer.