This invention is directed to the active matrix display device with an imaging speed rapid enough for the moving image display and the small power consumption. The selector makes the switch between the moving image mode, where the image signal consecutively inputted is consecutively displayed after the certain processing is performed by the data processing unit and the still image mode, where the display is made based on the image signal stored in the frame memory. The messy display upon the switching between the modes can be prevented by differentiating the switching timing of the still to moving image mode from that of the moving to still image mode, improving the display quality.