An organic light emitting display device includes a display panel, current measuring circuits, and a timing controller. The display panel includes a plurality of pixel blocks. The current measuring circuits measure driving currents of pixels in the pixel blocks. The timing controller adjusts data signals applied to the pixels based on values measured by the current measuring circuits. One of the current measuring circuits measure driving currents of the pixels in a corresponding one of the pixel blocks, and also a driving current of at least one overlapped pixel.