Indoor air quality(IAQ) problems are not limited to large office buildings that are inadequately operated. In fact, many school buildings have significant potentials of air pollution and indoor air pollutants may be of particular concern because it is estimated that most young students who are physically weak to the pollutants spend about 90% of their time in classrooms. The goal of the study is to provide academic and architectural information on the major factors that influence indoor air quality in the elementary school. In order to gain a better understanding of IAQ problems in schools, a series of measurement studies of indoor air quality were designed and 3 different elementary school buildings located in Chuncheon were selected. The levels of CO, $CO_2$, and total volatile organic compounds(TVOCs) including formaldehyde(HCHO), major concern of this study, were measured in absence of students after class. As the results, it is noticeable that most indoor air pollution comes from sources inside the building, which are, for example, adhesives, upholstery, manufactured wood products, art and scientific supplies. The level of CO was measured similarly to that of outdoors, which means no impact on the indoor air problems since it is lower than the code. Ventilation played an important role in the level of $CO_2$ of which difference was 1.7 times in rough and 230 % of difference in the level was detected among the 3 school buildings. This concludes that indoor air problems might be result of poor building design with inadequate location of corridors within space organization or occupant activity patterns of ventilation.