Naphthalene diimide derivative 1 carrying two 3-(ferrocenyl-methylamino)-propyl substituents was synthesized as a new hybrid indicator for electrochemical gene sensing. Ligand 1 showed a preference for double stranded DNA four-times larger than 2 previously described. The peak potential of 1 shifted 30 mV toward the negative side from that of 2, thereby shortening the time required for gene detection.