Interpenetrating polymer network (IPN) hydrogel composed of sodium alginate (SA) and poly(diallyldimethylammonium chloride) (PDADMAC) exhibited electrical-sensitive behavior. The SA/PDADMAC IPN hydrogel was synthesized using the sequential IPN method. The swelling behavior of the IPN hydrogel was studied by immersion of the gel in aqueous HCl solutions at various concentrations and pHs. The stimuli response of the IPN hydrogel in electric fields was also investigated. When swollen IPN hydrogel was placed between a pair of electrodes, the IPN exhibited bending behavior upon the application of an electric field. The IPN also showed stepwise bending behavior depending on the electric stimulus.