The research purpose for this study is to evaluate the quality of the KOLIS-NET DB which builded bibliographic data of the holding collections of nationwide public libraries. The quality evaluation of the KOLIS-NET DB was inspired by the successful experience from researches precedent and tried to approach the case study focuses on six quality dimensions : coverage, duplication. currentness. accuracy, consistency completeness. The study verified comprehensively the quality of the KOLIS-NET DB through a quality evaluation model and analyzed the factors causing such inferior and substandard bibliographic records in the KOLIS-NET DB. Based on the results of the quality evaluation, the quality improvements of the KOLIS-NET DB was suggested.