Polymer actuator and artificial lung device provided with same

A polymer actuator provided with: a pair of polymer films (12, 13) which are arranged to face each other; a pair of multiple electrodes (14, 15) which are formed on the pair of polymer films (12, 13) and arranged to face each other; a flow channel (20) which is formed between the pair of polymer films (12, 13) and through which a liquid flows; and a voltage application means which applies a voltage to the pair of electrodes (14, 15). The polymer films (12, 13) are expanded and contracted by applying a voltage to the pair of electrodes (14, 15).