A transparent organic light emitting display device having an improved transmittance, in which transmittance of external light is increased, the organic light emitting display device including: a substrate having transmitting regions interposed between pixel regions; thin film transistors positioned on a first surface of the substrate and respectively disposed in the pixel regions of the substrate; a passivation layer covering thin film transistors; pixel electrodes formed on the passivation layer and respectively electrically connected to the thin film transistors, the pixel electrodes are respectively located in an area corresponding to the pixel regions, and are disposed to respectively overlap and cover the thin film transistors; an opposite electrode facing the pixel electrodes and formed to be able to transmit light, the opposite electrode is located in the transmitting regions and the pixel regions and includes a first opening formed on a location corresponding to at least a portion of respective ones of the transmitting regions; and an organic emission layer interposed between respective ones of the pixel electrodes and the opposite electrode to emit light.