This paper describes the synthesis and properties of a novel molecular beacon (MB) containing a benzene-phosphate backbone at its stem moiety. The fluorescence intensity of MBs was found to stabilize by the introduction of the benzene-phosphate backbone at its stem moiety. Furthermore, an MB containing the benzene-phosphate backbone was more resistant to DNase I (endonuclease) than an MB comprising natural DNA and 2′-O-methyl-RNA. These results indicate that the MB with the benzene-phosphate backbone is superior as a molecular beacon as compared to the MB composed of natural DNA and 2′-O-methyl-RNA.