A display device is provided which includes: a still image detection unit (122) which inputs video signals having linear characteristic and calculates an average value of signal levels of the video signals having linear characteristic per pixel; a storage unit (150) which successively stores the average values calculated by the still image detection unit (122); a still image judging unit (162) which judges whether a still image is displayed on a present screen based on a difference between the average value stored in the storage unit (150) and the last average value; a coefficient calculation unit (164) which calculates coefficients for reducing luminance of an image to be displayed when the still image judging unit (162) has judged that a still image is displayed on the present screen; and a signal level correction unit (128) which multiplies the video signals by the coefficients calculated by the coefficient calculation unit (164).