The purpose of this study is to measure the saturation of the collection in public library and to propose a solution to this problem. In order to conduct this study, one local government was selected to measure the collection saturation status of each library and to clarify the cause of collection saturation. Based on the research results derived from this study, the public library in Korea measures the degree of collection saturation and recognizes the seriousness of collection saturation, and suggests the task of identifying the cause of collection saturation and solving it.