In order to establish the charge migration mechanism, we examined the electronic structure of bases in DNA strands by means of resonant photoemission spectroscopy near the Fermi level. Because the N atoms are only included in bases in DNA strands, the electronic orbital features of the bases can be specified selectively at the resonant excitation from the N core level to unoccupied states. On the obtained resonant photoemission spectra for both poly(dG) · poly(dC) and poly(dA) · poly(dT) DNAs, we observed a kinetic energy shift of N-KLL Auger electrons and an intensity enhancement of valence electrons. These results clearly show the localized unoccupied electronic states of the bases. Therefore, it is concluded that the charge hopping model is pertinent for the charge migration mechanism in DNA strands, when electrons pass through the unoccupied states.