An attempt to establish a systematic method to precisely evaluate the electrical conductivity of highly water-swollen polyelectrolyte gels was made. It was found that the electrical conductivity and the activation energy of fully ionized polyelectrolyte gel such as cross-linked poly(2-acrylamido-2-methylpropanesulfonic acid) gels with various counterions are almost identical with those of linear polymer in a wide range of swelling, indicating that the conduction of an ionic gel is essentially performed by the “free” counterions of Manning's condensation theory.