Provided is an organic light emitting display panel with uniform luminance. A flattening layer including a contact hole is disposed on a substrate on which an auxiliary electrode is disposed. The contact hole in the flattening layer has an undercut pattern at a point contacting the auxiliary electrode. The organic light emitting layer is disconnected by the contact hole, but the common electrode is connected with the auxiliary electrode at an undercut pattern portion with a high step coverage as compared with the organic light emitting layer. Since the auxiliary electrode and the common electrode are connected with each other through the contact hole having the undercut pattern in the flattening layer, it is possible to preserve uniform luminance of the organic light emitting display panel.