An organic light-emitting display device comprising: a display panel including a plurality of data lines, a plurality of first gate lines and a plurality of second gate lines, and a plurality of pixels; a data driver arranged to supply a data signal through at least one of the plurality of data lines; a first gate driver arranged to supply a sensing signal through at least one of the plurality of first gate lines that cross the plurality of data lines in the display panel; a second gate driver arranged to supply a scanning signal through at least one of the plurality of second gate lines that are substantially parallel with the plurality of first gate lines in the display panel; a timing controller arranged to control driving timings of the data driver, the first gate driver and the second gate driver, wherein each of the plurality of pixels includes an organic light-emitting diode, a driving transistor having a first node, a second node and a third node, a first transistor controlled by the sensing signal and connected between the respective data line and the first node of the driving transistor, a second transistor controlled by the scanning signal and connected between the respective data line and the second node of the driving transistor, and a storage capacitor (Cstg) connected between the first and second nodes (N1, N2) of the driving transistor, the third node being connected to a driving voltage line, wherein, in an emission mode, a driving voltage (EVDD) is supplied to the driving voltage line; and a sensing unit (1100, 2100) connected to the driving voltage line, the sensing unit (1100, 2100) comprising: an analog-to-digital converter adapted to measure a voltage of a sensing node (Ns) connected to the driving voltage line, or a current measuring unit adapted to measure a current flowing through the sensing node (Ns) connected to the driving voltage line, and a switch (Spre, Vsam) adapted to switch a connection between a precharge voltage supply node (Npre) and the sensing node (Ns) and switching a connection between a connection node (Nadc, Ni) of the analog-to-digital converter or the current measuring unit and the sensing node (Ns). a display panel including a plurality of data lines, a plurality of first gate lines and a plurality of second gate lines, and a plurality of pixels; a data driver arranged to supply a data signal through at least one of the plurality of data lines; a first gate driver arranged to supply a sensing signal through at least one of the plurality of first gate lines that cross the plurality of data lines in the display panel; a second gate driver arranged to supply a scanning signal through at least one of the plurality of second gate lines that are substantially parallel with the plurality of first gate lines in the display panel; a timing controller arranged to control driving timings of the data driver, the first gate driver and the second gate driver, wherein each of the plurality of pixels includes an organic light-emitting diode, a driving transistor having a first node, a second node and a third node, a first transistor controlled by the sensing signal and connected between the respective data line and the first node of the driving transistor, a second transistor controlled by the scanning signal and connected between the respective data line and the second node of the driving transistor, and a storage capacitor (Cstg) connected between the first and second nodes (N1, N2) of the driving transistor, the third node being connected to a driving voltage line, wherein, in an emission mode, a driving voltage (EVDD) is supplied to the driving voltage line; and a sensing unit (1100, 2100) connected to the driving voltage line, the sensing unit (1100, 2100) comprising: an analog-to-digital converter adapted to measure a voltage of a sensing node (Ns) connected to the driving voltage line, or a current measuring unit adapted to measure a current flowing through the sensing node (Ns) connected to the driving voltage line, and a switch (Spre, Vsam) adapted to switch a connection between a precharge voltage supply node (Npre) and the sensing node (Ns) and switching a connection between a connection node (Nadc, Ni) of the analog-to-digital converter or the current measuring unit and the sensing node (Ns). an analog-to-digital converter adapted to measure a voltage of a sensing node (Ns) connected to the driving voltage line, or a current measuring unit adapted to measure a current flowing through the sensing node (Ns) connected to the driving voltage line, and a switch (Spre, Vsam) adapted to switch a connection between a precharge voltage supply node (Npre) and the sensing node (Ns) and switching a connection between a connection node (Nadc, Ni) of the analog-to-digital converter or the current measuring unit and the sensing node (Ns).