We have synthesized and evaluated two types of functionalized oligodeoxynucleotides (ODNs) that can release a fluorescent coumarin probe via co-hybridization with a target DNA base sequence and subsequent photoirradiation. Photoirradiation of flavin-bearing ODN in the presence of a counterpart ODN with indolequinone-coumarin conjugate and a target complementary DNA strand gave rise to the efficient release of coumarin with a multiple turnover as a result of intermolecular flavin-photosensitized reduction of indolequinone-coumarin conjugate, while the release of coumarin was considerably suppressed in the absence of the target DNA. Concomitant with this photoreaction, we could observe intense fluorescence emission from the sample solution photoirradiated with the target DNA, but weak fluorescence from a control solution without the target DNA.