In a case where each of pixels of a liquid-crystal display panel is divided into two subpixels, the drive levels of the subpixels with respect to the gradation of an input video signal can be selected from among a plurality of drive levels while an increase in the circuit scale is suppressed.Thus, in the present invention, a first subpixel driving level converter for, on the basis of the gradation value of each pixel of the input video signal, obtaining a first gradation value for driving a first subpixel is provided, and the first subpixel is driven and controlled on the basis of the first gradation value. Then, the first gradation value obtained by the first subpixel driving level converter is converted into a luminance value, and a difference with the luminance value such that the gradation values of the whole pixels are converted is obtained. The obtained difference is converted into a gradation value, and a second gradation value for driving a second subpixel is obtained. The second subpixel is driven and controlled on the basis of the second gradation value.