A display device is provided that includes a transparent display unit, a setting unit that sets transparency of a first screen that is output in the foreground to the transparent display unit, and a controller that determines transparency of a background object that is seen through the transparent display unit, based on the transparency of the first screen that is set, such that the transparency of at least one of the background object and at least one region of the first screen is changed, based on a detected event that is associated with transparency control of the transparent display unit.