Twelve benzothiazolyl and 6-substituted benzothiazoly phenyl and chlorophenyl ureas have been newly synthesized by reacting 2-amino benzothiazole and 2-amino-6-substituted benzothazole with three or four phenyl and chlorophenyl isocyanate, respectively. The structures of these compounds were determined by measurement of the molecular weights and elementary analysis as well as IR spectrophotometry. The compounds generally exhibited antibacterial activity against Staphylococcus aureus and Escherichia coli in the concentration of $50mu g/ml$. The compounds containing chloro group exhibited stronger antibacterial activity than those containing methyl group against Eschichia coli. The difference in the antibacterial activity according to the substituted group (phenyl, o-, m-, and p-chlorophenyl) was also noted. The compounds containing o-chlorophenyl group, on the whole, exhibited more potent growth-inhibitory activity againsts staphylococcus aureus.