To provide a detoxification method of an organic halogen compound, using a supercritical fluid capable of detoxifying the organic halogen compound under a low temperature/low pressure compared to a conventional detoxification method of the organic halogen compound using the supercritical fluid.

Under supercritical carbon dioxide coexistence, an organic halogen compound and an alkali agent are brought into contact with each other under the conditions of being at or above the critical temperature of carbon dioxide and at or below the critical temperature of water and being at or above the critical pressure of the carbon dioxide and at or below the critical pressure of water, and the organic halogen compound is dehalogenated without using an oxidizing agent. At the time, water may be made to coexist.