An organic light emitting diode display device comprising: a substrate comprising a display region and a non-display region; a thin film transistor formed in the display region; a planarization layer formed on the thin film transistor; an anode formed on the planarization layer and connected to the thin film transistor through a contact hole formed in the planarization layer; an organic light emitting layer formed on the anode and connected to the thin film transistor; a cathode formed on the organic light emitting layer; a bank layer formed to define a light emitting region of the organic light emitting layer; a ground line formed in the non-display region along the outer periphery of the display region and not covered with the bank layer; a first conductive pattern connected to the organic light emitting layer and connected to the ground line, wherein the first condutive pattern is brought into contact with the cathode on the planarization layer; a second conductive pattern connected to the ground line and physically separated from the first conductive pattern, wherein the ground line comprises: a first metal pattern which is formed of the same material and in the same layer as a gate electrode of the thin film transistor; and a second metal pattern on the first metal pattern, which is formed of the same material and in the same layer as a source electrode of the thin film transistor, wherein the first metal pattern and the second metal pattern are electrically connected to each other by contact holes provided in an interlayer insulating layer formed between the first and second metal patterns (320G, 334G), wherein the second conductive pattern covers the ground line, and wherein the second conductive pattern comprises a plurality of parts physically separated from each other, or a bar whose length is parallel to the length of the ground line and whose width direction is parallel to the width of the ground line, the bar having a plurality of openings that expose the second metal pattern, are filled with a passivation film and are completely surrounded by material of the bar in planar view. a substrate comprising a display region and a non-display region; a thin film transistor formed in the display region; a planarization layer formed on the thin film transistor; an anode formed on the planarization layer and connected to the thin film transistor through a contact hole formed in the planarization layer; an organic light emitting layer formed on the anode and connected to the thin film transistor; a cathode formed on the organic light emitting layer; a bank layer formed to define a light emitting region of the organic light emitting layer; a ground line formed in the non-display region along the outer periphery of the display region and not covered with the bank layer; a first conductive pattern connected to the organic light emitting layer and connected to the ground line, wherein the first condutive pattern is brought into contact with the cathode on the planarization layer; a second conductive pattern connected to the ground line and physically separated from the first conductive pattern, wherein the ground line comprises: a first metal pattern which is formed of the same material and in the same layer as a gate electrode of the thin film transistor; and a second metal pattern on the first metal pattern, which is formed of the same material and in the same layer as a source electrode of the thin film transistor, wherein the first metal pattern and the second metal pattern are electrically connected to each other by contact holes provided in an interlayer insulating layer formed between the first and second metal patterns (320G, 334G), a first metal pattern which is formed of the same material and in the same layer as a gate electrode of the thin film transistor; and a second metal pattern on the first metal pattern, which is formed of the same material and in the same layer as a source electrode of the thin film transistor, wherein the first metal pattern and the second metal pattern are electrically connected to each other by contact holes provided in an interlayer insulating layer formed between the first and second metal patterns (320G, 334G), wherein the second conductive pattern covers the ground line, and wherein the second conductive pattern comprises a plurality of parts physically separated from each other, or a bar whose length is parallel to the length of the ground line and whose width direction is parallel to the width of the ground line, the bar having a plurality of openings that expose the second metal pattern, are filled with a passivation film and are completely surrounded by material of the bar in planar view.