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.
