To provide a method for dehalogenating an organic halogen compound, by which the dehalogenation of the slightly degradable halogen compound such as PCB can rapidly and surely be carried out with a metal sodium dispersion, and to provide a method for dehalogenating an organic halogen compound, by which the dehalogenated liquid can be post-treated to make the liquid harmless or reuse the liquid.

This method for dehalogenating an organic halogen compound is characterized by reacting a treating target material containing the organic halogen compound with a metal sodium dispersion and a dehalogenating agent containing a metal catalyst in a vessel to dehalogenate the organic halogen compound, and the method for dehalogenating the organic halogen compound, wherein the treated liquid is mixed with water to separate an oil layer from a water layer, is used.