The present invention relates to a gradation control method, for a display device, in which one frame is divided into a plurality of subframes and lighting times for pixels corresponding to the subframes are controlled based on the sum of respective light-emitting times in the subframes, so that gradations of the pixels are rendered; the frame is divided into n (positive integer) subframes (e.g., SF1′ to SF4′) in each of which m (positive integer)-bit data is set and a subframe (SF5′) in which p (positive integer smaller than m)-bit data is set. As a result, increase in a data setting time can be suppressed, even if the number of subframes is increased in order to enable complicated gradation control.