A display device includes a display panel and a control unit. The display panel includes a first substrate, a light modulation layer configured to switch between transmissive display and non-transmissive display, and a second substrate in this order, and further includes an optical sensor configured to detect a luminance of light incident from a first space located on one main surface side of the display panel and from a second space located on the other main surface side of the display panel. The control unit calculates, based on the luminance, a relationship between brightness of the first space and brightness of the second space as a numerical value and switches display of the light modulation layer based on the numerical value.