Abstract: A treating method and apparatus for treating a manganese containing water by crystalizing and removing a soluble manganese in a water to be treated containing carbonic acid ions by passing the water to be treated as an upward flow through a fluidized bed reaction tower having no support bed and containing manganese sand as a fluidized bed material and by adjusting a pH value of the water to be treated in said fluidized bed. A suspended manganese is also removed together with said soluble manganese in the water to be treated by forming a suspended solid in the water to be treated into a layer on said manganese sand fluidized bed by removing said layer of suspended solid. Further, a desired quantity of the treated water is introduced into the water to be treated for circulatory use.