An organic light emitting display device may have a pixel region and a transparent region, and may include a substrate, at least one semiconductor device disposed on the substrate in the pixel region, an organic light emitting structure disposed on the at least one semiconductor device, and a capacitor disposed on the substrate in the transparent region. The capacitor may have a sufficient capacitance without substantially reducing a transmittance of the organic light emitting display device. Additionally, the transparent region of the organic light emitting display device may serve as a mirror in accordance with the material included in a lower electrode of the capacitor and/or an upper electrode of the capacitor.