In a display using a time gradation method, as the number of the subframes in one frame period increases, the number of writings of video data to a pixel and the operating quantity of a driver circuit of the display increase so that power consumption increases. In a display device of the invention, one frame period is divided into n subframe periods using a display controller, the subframe periods are made to emit light or not, to express m-bit gradation by the total sum of lighting time in one frame period, and the number of subframe periods n provided in one frame period and the number of gradations m capable of being expressed are changed corresponding to each row arranged in matrix.