An organic light emitting display device includes a display unit including pixels coupled to scan lines and data lines, first and second power lines coupled to the pixels, a DC-DC converter configured to output first and second power sources to the pixels via the first and second power lines, respectively, and a short-circuit-sensing circuit configured to detect whether a short-circuit between the first and second power lines occurs, and configured to control an operation of the DC-DC converter when the short-circuit is detected, wherein voltage levels of the first and second power sources are configured to be changed in a frame period, the frame period including a reverse voltage application period in which the voltage level of the second power source is higher than that of the first power source.