PURPOSE: To provide a highly concentrated tribromophenolate aqueous solution high in stability and capable of being applied to various reactions.

CONSTITUTION: When a tribromophenolate aqueous solution is produced from tribromophenol and an alkali, a hydrophobic solvent, preferably a halogenated hydrocarbon such as chloroform or methylene chloride and a reducing agent such as a phenolic compound, sulfite or sulfide are added to the reaction solution to prepare a highly concentrated tribromophenolate aqueous solution having a concentration range of 60-80wt.%. Since the aqueous layer and the solvent layer can easily be separated from each other after the preparation of the tribromophenolate aqueous solution, the tribromophenolate can once be prepared in a large amount based on the volume of the reactor by removing the separated hydrophobic solvent and subsequently adding new tribromophenol.