A method of manufacturing an organic electroluminescent display device of the invention includes the steps of: forming, on a mother substrate including display regions and terminal forming regions, an upper electrode in each of the display regions; and cutting the mother substrate along each border between the display regions to thereby divide the mother substrate into a plurality of individual pieces. The step of forming the upper electrode includes the step of depositing a material of the upper electrode in the display regions using a mask including a frame-shaped frame and stripe-shaped shielding portions that cover regions corresponding to the terminal forming regions. The shielding portion is fixed in a state where the shielding portion spans between facing sides of the frame and tension in one direction is applied, and extends only in the one direction inside an inner periphery of the frame in a plan view.