Single-walled carbon nanotubes (SWNTs) consist of carbon atoms are pipe-shaped nano materials with a diameter of 10nm or less. Because SWNTs have outstanding mechanical, optical and electrical properties, they are widely used in industry. Recent studies have reported the toxicity of SWNTs. Toxicity assessment must take precedence in order to prevent environmental pollution. We proposed surface plasmon resonance based detection of single-walled carbon nanotube using DNAs. In this study, r-ssDNA (receptor single strand DNA) was immobilized on the sensor chip surface. SWNTs are wrapped by L1-ssDNA having complementary sequence of immobilized r-ssDNA. To enhance the sensitivity, L1-ssDNA SWNTs were aggregated via L2-ssDNA. The L1-ssDNA wrapping SWNTs bind to the r-ssDNA immobilized on sensor chip surface. Through this method, we effectively detect SWNT SPR sensor by 100pg/ml.