A display device includes a signal processing unit that receives input signals, and calculates output signals to a first sub-pixel, a second sub-pixel, a third sub-pixel, and a fourth sub-pixel. The signal processing unit calculates a frequency of pixels belonging to each of a plurality of partitions using a light quantity of a surface light source. The signal processing unit calculates an index value for each of the partitions by at least multiplying the cumulative frequency being obtained by sequentially adding the frequency of pixels from a partition having the maximum light quantity among the partitions, and the number of partitions representing a position of a partition to which the cumulative frequency belongs counted from the partition having the maximum light quantity. The signal processing unit controls luminance of the surface light source based on a partition in which the index value exceeds a threshold.