An image resolution enhancing device and method for a display panel are provided. The image resolution enhancing method includes the following steps. Enlarge the image resolution of a first image to obtain a second image. Shrink the image resolution of the second image to obtain a third image. Implement a subtraction operation on the first image and the third image, so as to obtain a difference image. Enlarge the image resolution of the difference image to obtain an enhancing image. Implement an addition operation on the enhancing image and the second image, so as to obtain a fourth image with high image resolution.