The present invention relates to an isothiazolone composition and a method for stabilizing the same, and particularly to an isothiazolone composition that does not comprise alkali earth metal salt of a divalent metal such as magnesium chloride, which causes salt shock, and thus that can be stably used as a sterilizer in a dispersion or emulsion such as paint acrylate or latex, therefore effectively preventing growth of microorganisms, and that has superior storage stability due to its low precipitation formation rate because it comprises a precipitation-preventing agent, and a method for stabilizing the same.