Liquid-crystalline elastomer carrying cyanobiphenyl side groups was synthesized by radical copolymerization of 6-(4’cyanobiphenyl-4-yloxy)hexyl acrylate and hexamethylene diacrylate. Liquid-crystalline elastomer was swollen in a low molecular weight liquid crystal. Swollen elastomer in the nematic phase quickly deformed by application of DC voltage. The response time of electrical deformation was determined by image analysis.