When a membrane system composed of two aqueous phases (W1 and W2) separated by a liquid membrane (M) was adopted and the potential difference EW1(A-B), was applied between two sites (sites A and B) in W1 near to the W1 \ M interface, the ion transport reaction from W1 at site A to W1 at site B through M (W1-->M-->W1 transport) was found to occur based on the voltammogram recorded by scanning EW1(A-B), and measuring the current between sites A and B. The efficiency of W1-->M-->W1 transport was higher when the ratio of the concentration of electrolyte in W1 to that in M was lower. An ion or electron transfer reaction at the W1 \ M interface in a region between sites A and B (site C) could be realized under the application of EW1(A-B). The ion transport from W2 to W1 through a domain formed in a part of M was also found to be possible under the applied EW1(A-B).