A display device that suppresses electric power consumption and displays an image with excellent quality is to be realized. A host control section (30) in accordance with an aspect of the present invention is a control device for a display device (1), said control device includes: an image determining section (35) for determining whether or not grayscale levels of a plurality of pixels in an image fall within a first range which consists of intermediate grayscale levels; and a driving changing section (36) for changing, according to a result of the determining carried out by the image determining section (35), a refresh rate of the display device (1).