A method of manufacturing an organic light emitting display includes: forming a transistor on a substrate; forming a cathode electrode on the transistor to be connected to a source or a drain of the transistor; forming a bank layer having an opening on the cathode electrode; allowing a natural oxide layer to form on the cathode electrode; removing the natural oxide layer from the cathode electrode; forming an insulating buffer layer on the cathode electrode; forming an organic light emitting layer on the insulating buffer layer; and forming an anode electrode on the organic light emitting layer.