An organic light-emitting display (OLED) device includes an anode, an organic emitting layer on the anode, and a cathode on the organic emitting layer. The cathode is configured to transmit at least a part of light emitted from the organic emitting layer and is formed of an alloy having a first metal and an oxide of a second metal. The cathode contains an alloy of a metal and a metal oxide and has an increased thickness, such that the process margin for the cathode can be improved.