An image over-driving device is provided. An image detection device detects a size and a moving speed of an object according to an image signal and outputs an over-driving control signal according to the detected size and moving speed. A first image register receives and temporarily stores first image data of the image signal in a first frame period, and receives second image data of the image signal and outputs the first image data as a buffer data in a sequential second frame period. A first over-driving unit includes first and second lookup tables recording different over-driving parameters. The first over-driving unit generates first and second over-driving signals according to the buffer data and the second image data respectively by using the first and second lookup tables. The first multiplexer selects the first or second over-driving signal according to the over-driving control signal to drive a display device.