An organic light-emitting display device includes a capacitor lower electrode that includes a semiconductor material doped with ion impurities. A first insulating layer covers an active layer and the capacitor lower electrode. A gate electrode includes a gate lower electrode formed of a transparent conductive material and a gate upper electrode formed of metal. A pixel electrode is electrically connected to the thin film transistor. A capacitor upper electrode is at the same level as the pixel electrode. An etch block layer is formed between the first insulating layer and the capacitor upper electrode. Source and drain electrodes are electrically connected to the active layer. A second insulating layer has an opening completely exposing the capacitor upper electrode. A third insulating layer exposes the pixel electrode. An intermediate layer includes an emissive layer. An opposite electrode faces the pixel electrode.