A chemical gas sensor based on single-walled carbon nanotubes (SWCNTs) with improved performance has been developed using a novel barricade-confronting electrode (BCE). This arrangement comprises two adjacent electrodes with tips separated by a narrow interval (2 µm). An induced centrifugal force caused the nanotube bundles on the sample surface to shift toward the gap between electrode. The sensor device demonstrated a better detection response toward NO2 and NH3 gases compared with existing sensors. The sensor devices developed with a BCE show a better detection response toward NO2 and NH3 gases compared with nanotube sensors fabricated with an interdigitated electrode geometry. Such an enhanced sensitivity of BCE-type devices can be explained as being due to nanotube bundle-bundle contact that occurs when the electrode gap is wider than the length of nanotube bundles. A more effective dispersion of nanotubes and a narrower separation of the electrodes (< 1 µm) are expected to contribute to the realization of enhanced sensor performance.