The concentrations of HCHO(formaldehyde), PM10(particulate matter), CO₂(carbon dioxide) and TBC(total bacteria counter) distribution in schools(Chung-Nam Area) were examined, and the results were compared with the recommended criterion of the administration law of indoor air. The subjects were an elementary school, a middle school and a high school in Chung-Nam area, and the concentration of TBC was examined by Single Stage Air Cascade Sampler, which applied the inertia collision catching method of 28.29L/min(flux) during 5 months from March, 2007 to July, 2007. The instrument(LD-3B, SIBATA Company)was used to examine PM10, by a light scattering method and a light transmission method. The instrument(Airboxx(KD Engineering) was used to examine CO₂. The instument(Z300XP(Environmental sensor)was used to examine HCHO. The result indicated that the PM10 average concentrations of the surveyed classrooms were 49 μg/m3 in Spring and 59 μg/m3 in Summer. The CO₂ average concentration of the surveyed schools were 576 ppm in the classroom and 527 ppm in the stateroom. The average concentration of TBC were 729 CFU/m3 in an elementary school, 401 CFU/m3 in a middle school, 381 CFU/m3 in a high school. The HCHO average concentration of the surveyed schools were 0.03 ppm in the classroom, 0.02 ppm in the stateroom.