DNAzymes represent catalytically active oligonucleotides that have been evolved via in vitro selections to site-specifically cleave RNA or DNA substrates.1,2 DNAzymes have become important tools for a variety of biochemical applications.And reversible photo-regulation of the DNAzyme function with high spatial and temporal resolution could be useful for many applications in biotechnology and biology.3-5 In the present study, a reversible photoresponsive DNAzyme that can be simply regulated by light irradiation with the change of its secondary structure was constructed.