We have reported that the natural DNA and DNAs intercalated with organic radicals were able to show the noble magnetic properties in dry state. Extending our study on the Magnetic properties of DNAs, we intercalated the photoresponsive proflavine (PF) molecules into DNAs when the intercalated DNA complexes were illuminated by a laser beam of 488 nm. Electron magnetic resonance (EMR) new signals appeared. We succeeded in measurement of photomagnetic properties of modified DNAs through electron magnetic resonance (EMR) spectroscopy and SQUID measurement. A significant increase in magnetization was observed for the photo-illuminated DNA/proflavine samples.