a substrate;

an actuator carried on said substrate to be movable along a linear axis between two operative positions past a neutral position, said actuator being adapted to be connected to an object for shifting the object, said actuator being formed on its opposite ends respectively with center electrodes with respect to said linear axis, and being resiliently supported to said substrate to be given a spring bias by which said actuator is biased towards said neutral position;

first and second side effectors carried on said substrate and disposed respectively on opposite ends of said actuator with respect to said linear axis; said side effectors being formed respectively with side electrodes that are held in electrostatically coupling relation with said center electrodes;

driving means which develops an electrostatically attracting force between said center electrode and said side electrodes for driving said actuator into either one of said two operating position;

latch means which latches said actuator in one of said operative position against said spring bias when said actuator is moved to said one position, and

unlatch means which unlatches said actuator to allow it to move out of said one operative position towards the other operative position,

wherein said side effectors are movable towards and away from said actuator along said linear axis between a normal position and a shifted position close to said actuator,

said unlatch means is interlocked with the movement of said side effectors in order to unlatch said actuator as one of said side effectors moves to it shifted position, thereby allowing said actuator to move out of one of said operative position and allowing it to move to the other operative position by the electrostatically attracting force developed between said one side effector and said actuator.