Formaldehyde is important because of its irritant and toxic properties, mutagenicity and carcinogenicity, In this study, liquid chromatography/mass spectrometry (LC/MS) was used for the analysis of formaldehyde after derivatization with 2,4-dinitrophenylhydrazine (DNPH) cartridge. Analytical parameters such as linearity, repeatability and minimum detection limit were evaluated. The linearity (r²) was 0.9999 when analyte concentration ranges from 50 to 400 ㎍/L. The relative standard deviation (%RSD) was 0.83% for the concentration of 400 ㎍/L, and the minimum detection limit (MDL) was 0.27 ppbv. We investigated the distribution of formaldehyde concentrations based on a total of 96 samples(industrial area : 32, complex boundary line : 32, affected (residential) area : 32) measured at the Shi-Hwa industrial complex from April to October 2006. By the statistical analysis of these measurement data, the average level of formaldehyde from industrial area, complex boundary line, and affected area was 2.7, 2.1, and 2.2 ppb during the daytime (10:00~16:00), and 1.4, 1.1, and 1.6 ppb during the nighttime (19:30~23:00), respectively. And also, we investigated the emission concentrations of formaldehyde from various emission sources of 33 individual companies located in the Shi-Hwa industrial complex from September to November 2006. The results of our study showed that the emission concentrations of formaldehyde greatly varied according to industrial and source types. The emission concentrations of formaldehyde showed in the descending oder of 11.4 ppm for insulation cable process, 2.0 ppm for sand casting process, 1.7 ppm for synthesis rubber process, and 1.3 ppm for hexamine process.