Disclosed are an organic light emitting display device to improve optical efficiency and prevent deterioration in reliability of thin film transistors, and a method of manufacturing the same. The organic light emitting display device includes a mirror wall which is disposed on a substrate such that the mirror wall surrounds a light emitting area of each sub-pixel where a light emitting element is disposed, thus preventing total reflection of light produced in the light emitting element and improving optical efficiency by reflecting light travelling toward a non-emitting area to be directed to the light emitting area.