A novel type of sulfotransferase, arylsulfate sulfotransferase (EC 2.8.2.22) purified from Haemophilus K-12, an intestinal bacterium of a mouse, was immobilized onto AH-S epharose 4B, CH-Sepharose 4B and DEAE-celluose. The enzyme was stabilized for storage more markedly by covalent immobilization onto AH-Spharose 4B or CH-Sepharose 4B and by adsorptive immobilization onto DEAE-cellulose than the free enzyme. The optimal pH and acceptor substrate specificity of immobuized enzyme were similar to those of the free enzyme.