In this study, the concentration distribution of radon, we analyzed from 55 house, 37 government office, 54 school from June 2008-June 2011 in Chungnam area. From the result of surveying indoor radon degree of 146 facilities, the annual average geometric concentration of indoor radon was 69.4 Bq/m3, 40.5 Bq/m3, 51.4 Bq/m3 in house, government office, school respectively. As for distribution of concentration based on seasons, the radon concentration showed the highest concentration in winter in all facilities. According to the result of the analysis by dividing the construction year, into before 60s, 60-70s, 80-90s and 2000s, the radon concentration was lower in all the newly constructed facilities. As for difference in radon concentration due to the presence or absence of basement, concentration of house, government office and schools having basement was 52.2 Bq/m3, 44.5 Bq/m3, 36.4 Bq/m3 that of having no basement was 75.2 Bq/m3, 53.6 Bq/m3, 67.4 Bq/m3 respectively. Place having no basement tend to show higher concentration. Keywords : Radon, Indoor air, School, House, Government office