PROBLEM TO BE SOLVED: To solve a problem of a heavy metal treatment agent containing an amine carbodithioate as an active ingredient that, when it is diluted and mixed with dilution water such as potable water, ground water, industrial water, and the like before being added to heavy metal contaminants, inorganic materials contained in the dilution water precipitate at the time of dilution and mixing as salts of poor solubility and thereby causes blocking of pipes, strainers, and the like.SOLUTION: Provided is a heavy metal treatment agent comprising an amine carbodithioate, a hydroxy amino carboxylic acid having three or more carboxyl groups, and/or a salt thereof, which is mixed with dilution water such as potable water, ground water, industrial water, and the like before addition to heavy metal contaminants.
