This study aims to evaluate the quality of Bibliographic database : The Union Catalog system(UNICAT) and Korean Library Information System Network(KOLIS-NET). The seven criteria(Coverage, Accuracy, Completeness, Currentness, Consistency on the quality of data itself and easy of use, Customer Support on the quality of database service) are used to measure their quality. The purpose of this study was dignose the quality of two bibliographic database mentioned above and analyses the measured result of quality comparatively and to find out the problems of them and also to provide possible suggestion for their improvements.