There are many studies reporting the average carbon dioxide levels in various indoor spaces. However, there have been a few studies showing how carbon dioxide concentration varied at many measurement points in one indoor space. In this study, the changes of indoor carbon dioxide concentration at classroom, library, and kindergarten were reported to find its carbon dioxide distribution change at various locations and altitudes. The maximum carbon dioxide concentration of the 3 sites were measured as 2,684, 2,295, and 1,526 ppm, respectively. These values exceeded the guideline concentration of 1,000 ppm for public places. The concentration of carbon dioxide was higher at upper area than lower area, and this is probably due to the rise of warm breathing air generated from students. In the upper area, the carbon dioxide concentration was higher at center area than four corners. However, in the lower area, the carbon dioxide concentration was higher at four corners than center area. Therefore, it could be concluded that the center of upper area is the best place for the installation of ventilation or carbon dioxide removal system.