Abstract: An actuator using a superelastic material characterized by a low heating temperature, excellent durability, and no necessity of composition adjustment is provided. An actuator (1) according to the invention includes a movable member operable in two directions, one direction and the other direction, and a pair of wire-like members made of a superelastic alloy and so attached to the movable member that the pair of wire-like members extend in the two respective directions and the same tensile force is applied thereto. The movable member is moved from a neutral position and left stationary in a predetermined position located along the one direction by applying a load to the movable member in the one direction and then removing the load, and the movable member is moved back from the predetermined position located along the one direction to the neutral position by applying a load to the movable member in the other direction and then removing the load.