A display device includes: a first detection unit that detects an external signal from a second external device via a second connection unit, and outputs a first detection result indicating presence of an external signal; and a control unit that determines whether the second external device is connected with a second input unit based on the first detection result, and performs control so that a video signal to be supplied to a display unit is switched from a first video signal to a second video signal to cause the display unit to display an image based on the second video signal in a case where the control unit that determines that the second external device is connected with the second input unit.