PURPOSE: To inexpensively obtain the subject compound useful as an intermediate, etc., for medicines, agrochemicals and optical materials, etc., while repeatedly using a fuming sulfuric acid solvent in high purity and yield by reacting a specific benzene derivative with gaseous chlorine using the fuming sulfuric acid solvent and an chlorine-based catalyst.

CONSTITUTION: (A) A compound of formula I [(n) is 0-6] is reacted with (D) gaseous chlorine using (B) a fuming sulfuric acid as a solvent in the presence of (C) an iodine-based catalyst such as I2 ICl3, ICI, KI or iodobenzene to provide the objective tetrachloropara-benzoquinone of formula II. Furthermore, in the component B, SO3 concentration is preferably 10-80wt.%, especially preferably 20-60wt.% and an amount of SO3 used is preferably 13-84mol, especially preferably 17-50mol based on 1mol compound of formula I.