An OLED display device is discussed which can include: a first substrate defined into an emission region and a non-emission region; a first electrode formed on the first substrate; a bank pattern configured to expose a part of the first electrode corresponding to the emission region; an organic emission layer formed on the exposed part of the first electrode corresponding to the emission region; a second electrode which includes a first conductive layer formed on the organic emission layer and a second conductive layer formed on the second conductive layer. The first conductive layer is formed from an alloy of magnesium (Mg) and silver (Ag), and the second conductive layer is formed from silver (Ag). Such an OLED display device allows the second electrode to include the first conductive layer and the second conductive layer. As such, a large-sized display device with low resistance and high transmittance can be realized.