1. A display device, comprising: an adjusting portion for adjusting the contrast of a video signal; a detecting portion for detecting a feature quantity of the video signal; a control portion for controlling a contrast adjusting operation of the adjusting portion according to a change of the feature quantity detected by the detecting portion; and a display portion for displaying a video image using the video signal having the contrast thereof adjusted by the adjusting portion, wherein the control portion controls the adjusting portion in such a manner that changes over time of a contrast gain when increasing the contrast gain of the video signal according to the change of the feature quantity detected by the detecting portion are more gradual than changes over time of the contrast gain when decreasing the contrast gain of the video signal according to the change in the feature quantity detected by the detecting portion.