DNA-mediated charge transfer has recently received a substantial attention because of its biological relevance in the DNA damage and DNA repair as well as the potential applications to nanoscale electronic devices In contrast to the numerous mechanistic studies on oxidative hole transfer (HT) through DNA our understanding of reductive electron transfer process still remains limited In this article, we demonstrate the results of direct observation of the excess electron transfer (EET) through DNA, which conjugated with aminopyrene (Py-A) and diphenylacetylene (DPA) as a photosensitizing donor and an acceptor of excess electron, respectively By inserting dihydrothymine as a spacer between Py-A and T or C, the yield of electron arrival to DPA was improved It was indicated that EET through DNA completed within a few or a few tens nanosecond time scale even for EET over 34 angstrom for both consecutive T and C sequences The various factors such as mismatch sequence and DNA length on the yield of electron arrival to DPA were examined