An organic light emitting diode display device includes a substrate, an active layer disposed on the substrate and including a metal oxide-based semiconductor, a gate electrode disposed on the active layer, an insulating layer disposed on the gate electrode, source and drain electrodes disposed on the insulating layer, a light emitting element on the source and drain electrodes, and a gate insulating layer between the active layer and the gate electrode. The gate insulating layer includes first and second gate insulating layers. The first gate insulating layer directly contacts the active layer and has a first amount of nitrogen. The second gate insulating layer is disposed on the first gate insulating layer and has a second amount of nitrogen that is different from the first amount of nitrogen.