A display device capable of operating at high speed and with low power consumption is provided. A miniaturized display device occupying a small area is also provided. The display device includes a support; a display portion which includes a pixel; a light-blocking unit which is in the support and includes a light-blocking layer having a first opening overlapping with at least part of the pixel, and a movable light-blocking layer blocking light passing through the first opening; a transistor which is electrically connected to the light-blocking unit and includes an oxide semiconductor film; and a capacitor electrically connected to the transistor.