An organic light-emitting device including: a light emitting diode that emits light by a signal current; a driving thin film transistor connected between a source voltage and a light emitting diode and connected at its drain to the light emitting diode and a current source, and that supplies the signal current to the light emitting diode depending on display data; a storage capacitor connected between the source voltage and a gate of the driving thin film transistor, and that stores the display data depending on a display data signal; a first switching unit connected between the drain of the driving thin film transistor and a data driver and connected at its gate with a first scan line, wherein the first switching unit and selects the data signal; a second switching unit connected between the gate and the drain of the driving thin film transistor and connected at its gate with a second scan line wherein, the second switching unit drives the driving thin film transistor; and a third switching unit connected between the drain of the driving thin film transistor and the light emitting diode and connected at its gate with a third scan line, wherein the third switch unit selects the signal current applied to the light emitting diode.