The present invention includes a display device for displaying an image and receiving light simultaneously or alternately. The display device includes: a plurality of display elements for displaying the image on a display surface of the display device by emitting light; a plurality of light receiving elements for receiving light incident on the display surface formed by the display elements; a storing unit for storing, as an initial value, a difference between two amounts of light received by the light receiving elements; and a detecting unit for detecting a state of contact with or proximity to the display surface and subtracting the initial value stored by the storing unit from a difference between the two detected amounts of received light.