A display device includes display pixels that display an image on a display screen. First and second optical sensors correspond to one or more of the display pixels and detect the amount of incident light. An optical member allows light coming from a first direction to enter the first optical sensors and light coming from a second direction to enter the second optical sensors. A memory circuit stores a first detection result that is detected in a first time period by means of the first optical sensors and stores a second detection result that is detected in the first time period by means of the second optical sensors. A comparison circuit compares sequential detection results to permit a judgment circuit to determine whether the display screen has been touched with a detection target medium.