A low-cost and simple fabrication technique is proposed to prepare the metal nanogap devices (MNGDs) of sub-50 nm size. Only currently available mass-production technologies such as photolithography and anodic oxidation of patterned metal films are utilized in the technique. The gap width of MNGD can be easily and accurately controlled by the applied voltage of the anodic oxidation process. For example, the gap width formed between titanium electrodes by anodic voltage 15 V is about 10 nm, and the standard deviation (sigma) of the width fluctuation is about only 2 mn (20% of the fabrication size). Thus, the accuracy of the fabrication technique is on the almost same level with the electron beam (EB) lithography. Multigap MNGD containing several different gap widths were fabricated for the use of deoxyribose nucleic acid (DNA) analysis. As an application of MNGD, pure water containing DNA was dropped on MNGD, dried in air and the current-voltage characteristics of DNA were measured. From,these results, it is expected that low-cost DNA analyzer can be provided by the present technique to fabricate MNGD. (C) 2003 American Vacuum Society.