To provide a system and method for accurately and effectively identifying individual bases of DNA or RNA.

This field effect transistor (FET), nucleic acid sequencing device (102) comprises source (106) and drain (104) regions, and gate oxide (136). Potential is applied to the source and drain by voltage source (112) through leads (116) connected to the source/drain metal contacts (123, 142). As nucleic acid strand (111) passes through an opening (118) which serves as the gate electrode region, the charge representative of a nucleic acid base (adenine, thymine, guanine or cytosine) modifies the current flowing between source (106) and drain (104) via a channel (119) by modifying the electric field therebetween and is measured by ammeter (114).