Haemophilus K-12 producing novel sulfotransferase was isolated from mouce intestinal flora. The enzyme catalyzed the transfer of sulfate group from p-nitrophenylsulfate to phenolic compounds. The optimum medium condition for the sulfotransferase production was 0.2% sucrose, 1% yeast extract, $Na_{2}HPO_4$ and 0.5% NaCl. The enzyme production was induced by donor substrate, but was not by accepters. When p-nitrophenylsulfate was used as a donor substrate, 1-naphthol was best substrate, followed by phenol, p-acetaminophenol and tyramine.