Chloromethylation of benzanthrone with sym-dichloromethyl ether in the presence of concentrated sulfuric acid gave a bis (chloromethyl) compound and the monochloromethyl compound was not obtained in this case. Decomposition of the his (chloromethyl) compound with chromic acid gave anthraquinone-l, 6-dicar-boxylic acid. This indicated that the chloromethyl groups were entered into Sand 9-positions in the same way as in cationoid reagent. A few derivatives were prepared from the bis-(chloromethyl) comound and the dyeing quapropertieslities of their pyridinium and iso thiuronium salts were examined.