PURPOSE: To provide an electrostatic actuator which is used for the positional control of a probe in a scanning tunneling microscope (STM) and in an information processing equipment utilizing the principle of STM and in the like, and whereby a large displacement can be obtained with a small driving voltage.

CONSTITUTION: On a fixed electrode 103, a dielectric thin film 104 is laminated. A movable piece 107 is provided thereon via an air gap 106. The movable piece 107 is held by a beam 121 in a rotatable way and with the structure of a double-end-supported beam. An electrostatic attractive force is generated by the applying of a voltage to the fixed electrode 103, and one end 107a of the movable piece 107 is contacted with the dielectric thin film 104. When the voltage applied to the fixed electrode 103 is increased in this state, the contacting area of the movable piece 107 with the dielectric thin film 104 is increased, and responding to this, a torque acts on the movable piece 107, and as a result, the other end 107b of the movable piece 107 is so displaced as to be separated from a substrate 101.