In a water treatment method, a first embodiment of the treatment method comprises the steps of producing electrolyzed acid water by electrolysis of raw water in an anode chamber of an electrolytic cell with an ion permeable partition membrane; removing volatile component in an acid property of the electrolyzed water; and producing electrolyzed neutral water without the volatile component by electrolysis of the electrolyzed acid water in a cathode chamber of the electrolytic cell.