An organic light emitting display device includes a display panel including a plurality of pixels, a scan driver configured to provide a scan signal to the pixels via a plurality of scan lines, a data driver configured to provide a data signal to the pixels via a plurality of data lines, and a readout circuit connected to the pixels via a plurality of readout lines, the readout circuit including a current-voltage converter configured to convert a current flowing through one of the readout lines into a first voltage, an analog-digital converter configured to convert the first voltage or a second voltage of the one of the readout lines into a digital data, and a switching circuit configured to control a connection among the one of the readout lines, the current-voltage converter, and the analog-digital converter.