In the aforementioned halogenation hydrogen salt where it designates 5 kuroro 2 methyl 4 isochiazorin 3 on as the active ingredient, weight % of moisture content 0.1 it uses the acetate below in the manufacturing process which includes, the cyclization process of the sulfide amide in order to offer the residue of the organic solvent which is used with the industrial manufacturing process and the shooting microbial medicine where content of the hydrolysate is decreased and the neutralization process of the halogenation hydrogen salt of the chemical compound which possesses 3 isochiazoron ring, as a reaction solvent of cyclization process, filters the acetate dispersed liquid of the halogenation hydrogen salt before the neutralization process and can weight % of moisture content 0.1 the hydrocarbon chemical compound belowAdding, the shooting microbial medicine where the organic solvent when it filters, does solvent exchange, at the same time, from cyclization process to solvent exchange weight % of moisture content 0.1 executing in the atmosphere which is below contains 5 kuroro 2 methyl 4 isochiazorin 3 on which can as the active ingredient, active ingredient density 10 weight % it is and total content of its hydrolysate are below 200ppm.5-クロロ-2-メチル-4-イソチアゾリン-3-オンを有効成分とし、その工業的製造工程で使用される有機溶媒の残留物及び加水分解物の含有量が低減された殺微生物剤を提供するための、スルフィドアミドの環化工程及び3-イソチアゾロン環を有する化合物のハロゲン化水素塩の中和工程を含む製造工程において、環化工程の反応溶媒として水分含有量0.1重量%以下の酢酸エステルを使用し、中和工程の前にハロゲン化水素塩の酢酸エステル分散液を濾過して得られる前記ハロゲン化水素塩に水分含有量0.1重量%以下の炭化水素化合物を添加して濾過し、溶媒交換をし、かつ、環化工程から溶媒交換までを水分含量0.1重量%以下の雰囲気中で実施して得られた5-クロロ-2-メチル-4-イソチアゾリン-3-オンを有効成分として含有し、有効成分濃度が10重量%である場合の有機溶媒及びその加水分解物の合計含有量が200ppm以下である殺微生物剤。
