Water quality management device, water treatment system, water quality management method, and water treatment system optimization program

The water quality of a circulating water system is appropriately managed even when the quality of makeup water is not constant. A water quality index value acquisition unit for acquiring a water quality index value including a makeup water quality index value indicating the quality of makeup water and a circulating water quality index value indicating the quality of circulating water, and a water quality index acquired by the water quality index value acquisition unit And a determining unit that determines a concentration control amount related to the concentration rate of the circulating water system based on the value. [Selection] Figure 1