1. An apparatus for detecting an afterimage candidate region, comprising: a comparison unit which compares gradation data of an n-th frame with integrated gradation data of an (n−1)-th frame and generates integrated gradation data of the n-th frame, wherein n is a natural number; a memory which provides the integrated gradation data of the (n−1)-th frame to the comparison unit and stores the integrated gradation data of the n-th frame; and an afterimage candidate region detection unit which detects the afterimage candidate region based on the integrated gradation data of the n-th frame, wherein each of the integrated gradation data of the n-th frame and the integrated gradation data of the (n−1)-th frame comprises a comparison region and a gradation region.