Embodiments of the disclosure relate to a controller and a display device. As the display device is driven, the stress value is accumulated, and a compensation value based on the accumulated stress value is applied upon driving the display. Thus, it is possible to compensate for degradation of subpixels in real time. Further, the amount of degradation of the subpixel is sensed at a preset time, and the stress value is corrected based on the degradation amount sensing data. Thus, it is possible to enhance the accuracy of real-time compensation for degradation of subpixels while minimizing sensing of degradation of subpixels.