An object of the present invention is to provide a small-sized active matrix type liquid crystal display device that may achieve large-sized display, high precision, high resolution and multi-gray scales. According to the present invention, gray scale display is performed by combining time ratio gray scale and voltage gray scale in a liquid crystal display device which performs display in OCB mode. In doing so, one frame is divided into subframes corresponding to the number of bit for the time ratio gray scale. Initialize voltage is applied onto the liquid crystal upon display of a subframe.