Imipenem, as a representative of-cabapenem, is one of the most effective beta-Lactam agents against Bacteroides, but recently there have been a few reports on the resistant strains of Bacteroides. To explore the mechanism of imipenem resistance (IMPr) at the molecular level, we extracted chromosome DNA of the resistant strains and acquired a 1.7 kb fragment of resistant gene of imipenem. Recombinant plasmid was stably reserved in generation after generation in E. coli DH5. Resistant gene of imipenem was labeled with Dig-11-dUTP by way of random prime, and 40 strains of clinically isolated Bacteroides were detected by the prepared DNA probe. Two IMPr strains showed hybridization signal, whereas 38 IMPr strains did not show such a signal. The result suggests that the Dig-labeled IMPr gene probe can be used in molecular epidemiology for investigating IMPr strains.