PROBLEM TO BE SOLVED: To provide an agent that cleans water of sea, river, lake, etc. renders the water suitable for growing fish, for example, and contributes to solutions to global environmental issues by enhancing carbon dioxide absorption from the water.SOLUTION: A water cleaning agent is produced by steps of: using a base material composed of pulverized powders of a mineral group containing mineral species generating terahertz waves and iron powders; further adding to the base material one or two among carbon contents, pulverized powders of coral, and bamboo ashes; and adding paste type rice and molding those components after adding paste type rice as a binder. The water cleaning agent is cast into water of river, lake, sea, etc., as it is or after adding liquid containing one or more among yeast, lactic bacteria, and Bacillus natto.SELECTED DRAWING: NoneCOPYRIGHT: (C)2018,JPO&INPIT【課題】海、河川、湖沼などの水を浄化して、たとえば魚類などの養殖に適した状態にするとともに、水の炭酸ガス吸収促進を通して、地球環境問題の改善に貢献する。【解決手段】テラヘルツ波を発生する鉱物種を含む鉱物類を粉にしたものと鉄分の粉を加えたものを基本とし、それにさらに炭素分を加えたもの、サンゴを粉にしたもの、竹灰のうちの1つあるいは2つを加えたもの、また、ご飯をのり状にしたものを粘結材として加えて成型したものをそのまま、あるいは酵母、乳酸菌、納豆菌の1つあるいは2つ以上を含む液を加えてから河川、湖、海などの水中に投入する。【選択図】なし