It must be immediate ready for possible chemical terrorism that might range from water or food contamination. In April 2012, there has been real pesticide attack in small scale drinking water facility at Hongsung area. Early detection of any terrorism is dependent on a strong public health system. The objective of this study was to develop a high-speed and accurate analytical method to identify pesticides in water using direct analysis in real time (DART) ionization and accurate mass scanning by Orbitrap mass spectrometry. Ionization temperature and time for DART were set at 300℃ and 30 s, respectively. Resolution, scan range and mass accuracy for Orbitrap mass spectrometry were operated at 50,000, 100∼500 and 5 ppm, calculted parts per million unit of monoisotope, respectively. Xcalibur 2.1 was used for identification and mass accuracy test. Protonated molecular ions and carbon or chlorine isotopes for tested compounds were identified within 1 ppm mass accuracy. Acetochlor (C_14H_20ClNO_2) was randomly selected for sensitivity test. Protonated molecular ion m/z 270.1258 and chlorine isotope for identification m/z 272.1231 were detected with ratio of 3:1 for 100 to 1 ng/mL. This indicated that this approach is a sensitive and available direct analysis without sample preparation in case of urgent accidents.