An OLED display device includes a driving semiconductor layer on a substrate, a gate insulating layer covering the driving semiconductor layer, a driving gate electrode and etching preventing layer on the gate insulating layer, a passivation layer on the gate insulating layer, driving gate electrode, and etching preventing layer, and including a plurality of protruding and depressed patterns, driving source and drain electrodes on the passivation layer, a pixel electrode on the protruding and depressed pattern, and exposed etching preventing layer, the pixel electrode having a protruding and depressed shape, a pixel definition layer on the passivation layer, and the driving source and drain electrodes, and having a pixel opening exposing the pixel electrode, an organic emission layer on the exposed pixel electrode, and a common electrode on the organic emission layer and pixel definition layer. The protruding and depressed pattern partially exposes the etching preventing layer.