A material with variable viscoelasticity is composed of an electrically insulating polymeric material, and fine particles dispersed therein and capable of electric polarization under an applied electric field. The particles may, for example, be of a conjugated and unsaturated organic compound, a polyelectrolyte, or an organometallic complex salt. The material is capable of a reversible change of viscoelasticity depending on the intensity of the applied electric field.