Mercury contamination and its health effects have become major concern of environmental health study in Korea. Mercury exposure of some group were investigated to get the accurate data for policy making and study. About 2,000 children at 26 elementary schools participated in this survey to evaluate the exposure levels and to investigate main exposure source of mercury. Analysis of mercury levels in the whole blood and urine samples were conducted and questionnaire survey was done about the factors influencing exposures simultaneously. Mercury exposure levels of domestic children were N.D. to 17.26ppb in blood, 0.17 to 21.67mg/g-creatinine in urine. The mean(arithmetic) levels are 2.42ppb in blood and 2.53mg/g-creatinine in urine. Both of them were below the recommendation levels of US EPA and German CHBMI 5.8mg/l and 5mg/l in blood, 5mg/g-creatinine of German CHBMI in urine. But 1%, 0.51% of levels in blood exceed the level of CHBMI and US EPA, 8%, 0.85% of children were over the level of CHBMI and CHBMII in urine. Multi-valuable regression analysis showed that the existence of road near the residence in addition to the preference for fish have significance with blood mercury exposure level of domestic children. The existence of factory near the house and the experience of dental amalgam treatment had statistical relations with urine mercury level.