A production system of electrolyzed ion water wherein acid ion water and alkaline ion water are produced by electrolysis of water or brine between a pair of electrodes in an electrolyzer and discharged through discharge conduits for use in appropriate manner, and wherein DC voltage between the electrodes is inverted in polarity to eliminate contaminants adhered to the negative electrode in the electrolyzer. In the production system, invert ion water produced in the electrolyzer at a cleaning mode is discharged in such a manner as to be used as proper ion water, and the contaminants are eliminated without causing entry of the invert ion water into a storage tank of proper ion water.