Objective: Saga University has the “Saga Forum of Environment” project conducted in collaboration with the Saga city local gavarment. In this project, a workshop was held to study the sick building syndrome at schools. The purpose of this workshop was to evaluate indoor air pollution levels in elementary and junior high schools in Saga city. Methods: The levels of aldehydes and volatile organic compounds (VOC) were measured in 96 classrooms of the 49 schools in August. The sampling of these chemicals were performed by the passive sampler method and measured by high-performance liquid chromatograph or gas chromatograph—mass spectrometer by participants of the workshop. Results: In 40% of all classrooms, formaldehyde levels were higher than that of the standard of Japanese Ministry of Education. Relatively high levels of formaldehyde were found in some music classrooms. The origin of formaldehyde was thought to be musical instruments, furniture or wooden floors. A significant correlation was found between formaldehyde level and room temperature. The classrooms with ventilators showed lower levels of formaldehyde than those without ventilators. The levels of most VOCs except that of α-pinene were low. Conclusion: There is still room for improvement of air pollution in elementary and junior high schools.