Recently, indoor air quality (IAQ) in workplace, residence, and schools has been one of the major concerns of people, scientists and the related public. This study was performed to investigate the characteristics of indoor air quality(IAQ) in kindergartens, elementary school, middle schools, and high schools from June 2004 to May 2005 in Korea. We measured indoor air pollutants such as PM10, CO2, formaldehyde, total bacteria colony(TBC), CO, radon, total volatile organic compounds(TVOCs), asbestos, and O3 from school classrooms. The subjects were classified by building year based on the time span of 1, 1-3, 3-5, and 5-10years. The levels of pollutants and physical factor in schools were compared with standards and guidelines of indoor air quality on the Ministry of Environment, the Ministry of Health and Welfare, and the Ministry of Education, and Human Resources Development of Korea. The major results obtained from this study can be summarized as follows. Asbestos and O3 were not detected in all surveyed classrooms. However, we were able to detect CO, TBC, TVOCs, and formaldehyde in kindergartens, TBC in elementary schools, TBC, TVOCs and formaldehyde in middle schools, and formaldehyde in high schools. This study was conducted to provide a basis for the management IAQ in school. Therefore, we suggest that a national plan for the management of IAQ in school should be established through a long-term, continuous investigation for the proper assessment of IAQ in school and for the health risk assessment for student. Key Words：Kindergarten, Elementary school, Middle school, High school, Indoor air quality(IAQ), Physical factors, Indoor air pollution(IAP).