To provide a sight controllable display device that is capable of switching a regular display and a concealed display easily. A display panel and a modulator are disposed between two polarizing plates. The display panel performs a regular display drive. Meanwhile, the modulator drives to operate at a speed faster than twice the speed of the display panel and modulate the display image of the display panel. When displaying an image that is desired to be concealed, the period where the modulator is not in action is selected and viewed by a shutter. By stopping the action of the modulator, the regular display can be viewed as it is without the shutter.