Abstract: A detecting chip (2) comprising a body (5) and a frame (4) both detachable from each other. A large number of projecting pin electrodes (10) are arranged in a matrix inside the body (5). Oligonucleotide consisting of different gene sequences is fixed to the pin electrode (10). A common electrode is so disposed in a recess (8) in a frame (4) as to be out of contact with the pin electrodes (10). A DNA sample is placed in the recess (8). By applying a voltage between the common electrode and the pin electrodes (10), a current is detected to detect a hybridized two-strand DNA, thus analyzing a gene DNA.

Abstract: Space part S within a detecting chip 2 for single base substitution SNP and point mutation of genes where a plurality of gold electrodes 8 are formed in the base 7 of closed space part S, oligonucleotides 10 with different gene sequences are fixed to the gold electrodes 8, a common electrode 16 arranged not to contact the gold electrodes 8, are filled with DNA samples, voltage is applied between the common electrode 16 and the gold electrode 8, and current is measured to allow the double-stranded DNA to be detected and analyzed. It becomes possible to detect and analyze a large number of single base substitution SNP and point mutation for a plurality of DNA samples.