Abstract: An electrolytic apparatus and a method produce slightly acidic electrolyzed water with a molecular hypochlorous acid component by electrolysis of a chlorine containing composition. The electrolytic apparatus electrolyzes a chlorine containing composition with chloride ions and then dilutes the electrolyzed solution, and includes a container for providing a dilution water passage for diluting the electrolyzed solution, an electrode stack in the container including a diaphragm-less unit electrolysis cell defined between planar electrodes and the electrode holder frame for supplying chlorine composition at the position corresponding to the unit electrolysis cell, and an electrode holder frame including a reservoir part fluid-communicated to the opening while retaining the chlorine containing composition prior to the supply of the chlorine containing composition to the unit electrolysis cell.