PROBLEM TO BE SOLVED: To provide a manufacturing apparatus of water for preparing dialysate capable of correctly evaluating the removal capacity of impurities in a reverse osmosis membrane treatment device, and keeping the concentration of dissolved hydrogen in treated water at a desired concentration.SOLUTION: A manufacturing apparatus 1 of water for preparing dialysate comprises: a reverse osmosis membrane treatment device 6； an electrolytic water producing device 7 for performing electrolytic treatment of water using a solid polymer membrane； a sensor 31 for detecting the concentration of dissolved hydrogen in water flowing into the electrolytic water producing device 7； electrolytic current determination means 33 for determining electrolytic current in the electrolytic treatment by the electrolytic water producing device 7； electrolytic current supplying means 34 for supplying the electrolytic current to the electrolytic water producing device 7； and storage menas 35 for storing data about a target value of the concentration of dissolved hydrogen. The electrolytic current supplying means 33 determines the electrolytic current on the basis of the comparison result of a value of the concentration of dissolved hydrogen detected by the sensor 31 and the target value of the concentration of dissolved hydrogen stored in the storage menas 35.
