A shutter device includes a stationary plate having a plurality of driving
electrodes movable element opposes the stationary plate and including a
sheet subjected to an electret-forming process. A drive control unit for
moving the movable element using variation in electrostatic force,
thereby shielding light. The electrostatic force is generated between
constant charges held in the movable element as a result of the
electret-forming process, and charges generated in each of the driving
electrodes when a voltage is applied to each driving electrode. The
generated electrostatic force is varied by varying the voltage applied to
each driving electrode.