A polymeric actuator of simple structure, capable of being easily miniaturized, showing quick response and capable of generating large displacement. The polymeric actuator includes an ion-exchange resin product and metal electrodes. The ion-exchange resin product contains an alkylammonium. The metal electrodes are formed on the surface of the ion-exchange resin product and are insulated from each other. The polymeric actuator operates as an actuator by applying a potential difference between the metal electrodes when the ion-exchange resin product is in water-containing state to allow the ion-exchange resin product to undergo bending or deformation.