The continuous extraction of penicillin G with a liquid surfactant membrane containing di-n-octylamine as a carrier and Paranox 100 as a surfactant was carried out by using Vibro Mixer(R) under various operating conditions. Vibro Mixer(R), which had spiral-shaped blades on the shaft oscillated by a motor, was a new cocurrent extractor. The extent of extraction under the optimum conditions was 85-90%. From the analysis of response measurement against pulse input, the liquid flow of continuous phase was found to approach the perfectly mixed flow with the increase in stroke frequency. By analyzing Vibro Mixer(R) with a dispersion model, mass transfer coefficient and interfacial reaction rate constant were evaluated.