The purpose of this study was to investigate the health risk and management of childhood exposure to indoor aldehydes in elementary-schools and academies. The samples were collected at children\'s facilities (50 elementary-schools and 46 academies) in summer (Aug ~ Sept, 2008), winter (Dec 2008 ~ Feb, 2009) and Spring (Mar ~ Apr, 2009) periods. The overall mean concentration of formaldehyde was 68.3 ㎍/㎥ and 27.2% of exceeded the 100 ㎍/㎥ by the school health guideline. The concentration ratio of Indoor air and outdoor air (I/O) of aldehydes exceeds 1.0. The level of indoor air contamination did appear to be high, and 24.6% of the academies evaluated had exceeded the formaldehyde level specified by the public health act (120 ㎍/㎥). We estimated the lifetime excess cancer risks (ECRs) of formaldehyde, and the hazard quotients (HQs) of non-carcinogens (acetaldehyde and benzaldehyde). In addition, for carcinogens, the excess cancer risk (ECR) was calculated by considering the process of deciding cancer potency factor (CPF) and age dependent adjust Factor (ADAF) of the data of adults. The average ECRs of formaldehyde for young children were 1×10-6~1×10-5 level in all facilities. HQs of formaldehyde did exceed 0.1 for all subjects in elementary school. Keywords : Aldehydes, Health risk assessment, Elementary-schools, Academies