Abstract: Disclosed is a liquid filter device for effectively eliminating impurities from liquid.Voltage is applied to liquid to break electrostatic coupling of liquid molecules and impurity molecules. The impurity molecules are electrostatically adsorbed by an electrode containing adsorbent having charges different in polarity from those of the impurity molecules.Voltage is applied to liquid to break electrostatic coupling of liquid molecules and impurity molecules. Adsorbent having charges different in polarity from those of the impurity molecules on its surface is provided between a pair of electrodes to electrostatically adsorb the impurity molecules. After the impurity molecules are electrostatically adsorbed, the liquid is filtrated by a filter.Voltage is applied to liquid to eliminate zeta potentials which are potential difference at electric double layers having charges different in polarity from those of impurity particles in interfaces between the impurity particles and the liquid.