The present invention provides a polymeric actuator which has excellent flexibility and elongation rate; low temperature dependability of physical properties such as an elastic modulus and high dielectric breakdown strength, and which can drive in a low electric field. The present invention relates to a polymeric actuator, wherein the polymeric dielectric has a storage elastic modulus at 20° C. [E′(20° C.)] determined by a dynamic viscoelastic measurement at a frequency of 1 Hz of not more than 0.5 MPa, a ratio [E′(−20° C.)/E′(20° C.)] of a storage elastic modulus at −20° C. [E′(−20° C.)] determined by a dynamic viscoelastic measurement at a frequency of 1 Hz to the [E′(20° C.)] of not more than 5.0, and a ratio [E′(40° C.)/E′(20° C.)] of a storage elastic modulus at 40° C. [E′(40° C.)] determined by a dynamic viscoelastic measurement at a frequency of 1 Hz to the [E′(20° C.)] of not less than 0.5.