Management process of apartment buildings construction has increased because the after service of construction company meet the needs of customers. Many defect data, which was inspected by construction company or customers before moving into a new apartment house, were classified by field engineers and then communicated to corresponding subcontractors. The classification process needs to be performed by an expert engineer because there is so much data, it is unfeasible to complete in a short period of time. For this classification process, an automatic classification system using case base reasoning (CBR) should be considered. This research proposed a defect management system with automatic classification system using CBR. This constructed defect management system consists of cyber after service system for tenants and the whole defect management process of construction, preservation and management of apartment buildings. This system could improve the efficiency of expert work in terms of time and accuracy, as well as helping laymen users to conduct defect classification work as experts do.