An organic electroluminescent device is provided. A gate line and a data line cross each other to define a pixel region, and a power line crosses the gate line and is arranged parallel to the data line. A switching transistor is disposed at a crossing of the gate line and the data line, a driving transistor is disposed at a crossing of the gate line and the power line, and a pixel electrode is formed in the pixel region. Each of the switching transistor and the driving transistor includes a gate electrode formed under a channel layer, and a stopper on the channel layer.