Problem to be solved: to provide a wet coating booth circulating water treatment agent and a method of treating the water paint booth to increase the drastic use of the water-based paint and to solve the serious fouling of the booth circulating water by the complicated type and diversification of the operation type and the failure due to the high concentration of volatile components.Solution: the wet coating booth circulating water treatment agent containing the Benzoylhydrazine compound of the formula (1) or benzoyl urea compound or diphenyl ether compound and the treating method.Diagram【課題】湿式塗装ブースにおける、水性塗料の大幅な使用増加と運転形式の複雑化や多様化によるブース循環水の深刻な悪臭や高濃度の濁質成分による障害を解決できる湿式塗装ブース循環水処理剤及び処理方法を提供する。【解決手段】下記式（１）のベンゾイルヒドラジン化合物、又はベンゾイル尿素化合物、又はジフェニルエーテル化合物を含有する湿式塗装ブース循環水処理剤及び処理方法。【選択図】図１
