In one embodiment of the present invention, to time-divide one frame of an input image signal into a first-half sub frame and a second-half sub frame, the grayscale of the signal in the second-half sub frame is set at a grayscale for dark display and the grayscale of the display signal of the first-half sub frame is adjusted, when the input image signal indicates low brightness. When an image with high brightness is displayed, the grayscale of the display signal of the first-half sub frame is set at a second predetermined value smaller than the maximum value and the grayscale of the display signal of the second-half sub frame is adjusted. Thereafter, in accordance with a combination of the input image signals of the (N-1)-th frame and the N-th frame, overshoot is performed with respect to the display signal of the first-half sub frame.