A mobile terminal controls a display unit to display a first image in a first display area at a first luminance and to display a second image in a second display area at the first luminance, under a first condition in which brightness measured by a optical sensor is lower than a first threshold, and controls the display unit to display a third image in the first display area at a second luminance that is higher than the first luminance and to set a luminance in the second display area to a third luminance that is lower than the first luminance, under a second condition in which the measured brightness is equal to or higher than the first threshold, a content of the third image being determined so as to include a content of the first image and a content of the second image.