In this paper, we present a novel actuation method employing dielectric elastomer and a micro--inchworm robot actuated by the proposed method. Different from the previous approaches adopting pretensions of dielectric elastomer, the method depends solely on the deformation caused by the Maxwell stress, and thus, their critical problem such as stress relaxation as time goes on is cleared, though the amount of deformation is largely reduced. In addition, the proposed actuation method provides advantageous features of reduction in size, speed of response, ruggedness in operation. Using the actuator, a three-degree-of-freedom actuator module is developed, which can provide up-down, and two rotational degree-of-freedom motion. In the application of the proposed actuation method, a micro-robot mimicking the motion of an inchworm is developed.