A gradation conversion unit 23 performs, on an input image, gradation conversion in which a predetermined gain is applied to a gradation smaller than a boundary gradation CVth and a characteristic becomes a spline curve for a gradation larger than the boundary gradation. To determine a characteristic of the gradation conversion unit 23, an image analysis unit 22 obtains the boundary gradation CVth and a maximum gradation CVmax based on the input image, and determines a linear gain shift coefficient LGs so that the brightness decreasing rate of the maximum gradation CVmax when brightness control of a backlight 30 is performed becomes a limit value or less. In such a manner, power consumption of the backlight is reduced while suppressing deterioration in picture quality.