Abstract: To detect the presence of a match of a target DNA base sequence with a probe DNA base sequence, a single strand of the probe DNA base sequence is prepared. One end of the single strand probe DNA base sequence is linked to an electrode and the other end to a nano entity capable of exchanging charge with the DNA base sequence. The single strand of the target DNA base sequence is brought into contact with the single strand of the probe DNA base sequence, and the change in the physical properties of the probe DNA base sequence upon hybridization detected.