A method for removing chlorinated organic compounds efficiently by improving reactivity of iron minerals is provided, and a method for removing the chlorinated organic compounds from water or soil contaminated with the chlorinated organic compounds in situ or ex situ is provided. A method for removing chlorinated organic compounds comprises the steps of: (a) adding the transition metals to reductive iron minerals in a solution comprising transition metals to obtain catalyst-added iron minerals; and (b) injecting the catalyst-added iron minerals into a removal object comprising the chlorinated organic compounds. The reductive iron minerals contain at least one selected from the group consisting of iron sulfide, magnetite, and green rust. The chlorinated organic compounds contain at least one selected from perchloroethylene, trichloroethane, and trichloroethylene. The method comprises injecting iron sulfide-containing catalyst-added iron minerals into the removal object in such an amount that a molar ratio of i
