The present invention relates to a micro-electromechanical system (MEMS) and, more particularly, to an electrostatic actuator, and a driving method thereof and an application device thereof. The electrostatic actuator in accordance with the present invention comprises a fixed electrode, an electric charge charging unit electrically insulated from the fixed electrode, and a moving electrode spaced apart from the fixed electrode and the electric charge charging unit. In accordance with the present invention, the electrostatic actuator with a very low driving voltage and an arbitrarily controllable driving voltage when compared with a conventional electrostatic actuator is provided. In addition, the electrostatic actuator having durability against external noise and enabling a reliable consecutive operation is provided. Further, in accordance with the present invention, non-volatile mechanical memory, a logic circuit and a switch employing the electrostatic actuator are provided.