It is an object of the present invention to reduce a cause of pseudo contour when display is performed with a time gray scale method. According to the present invention, one pixel is divided into m sub-pixels so that an area ratio of each sub-pixel becomes 20:21:22: . . . :2m-3:2m-2:2m-1 (m is an integer number of m≧2), and one frame is divided into n sub-frames so that a ratio of a lighting period in each sub-frame becomes 20:2m:22m: . . . :2(n-3)m:2(n-2)m:2(n-1)m (n is an integer number of n≧2). Then, a gray scale is expressed by controlling a manner of lighting in each of the m sub-pixels in each of the n sub-frames.