Periodic oscillations of electric potential were induced by DC electric current between identical salt solutions separated by a membrane filter impregnated with triolein. The oscillation period was controlled by the base electric potential, and temperature dependence of base conductance and conductance amplitude were both close to that of the electric conductivity of the aqueous salt solution. Effects of salt concentration on membrane conductance and on oscillation characteristics were experimentally investigated, and the lifetime of the membrane and of each oscillation were much improved by regulating the concentration of the salt solution. Moreover, characteristics of oscillation curves could be controlled. All the experimental results could be explained by a model where the oscillation was generated by a periodic change of the diameter of a hole through the membrane, which opened in one of the pores filled with triolein.