This study measures the efficiency of public libraries, library services, and management to contribute to the proposed model for efficiency analysis, reflecting the characteristics in public libraries. This analysis model of applying the empirical research pursues the solutions to provide efficiency. Although many attempts have been made domestically and internationally to study the measurement of the efficiency, mere application of analysis techniques used in the other public sectors has led to the inadequate measurement for characteristics of library services. In addition, there has not been any attempt made to deduce a general theory for the study from the measurement results. In this study, an analysis model that reflects the inherent characteristics in library services is suggested to be analyzed empirically, and this leads to the understanding of efficiency factors. The results of the study show that the efficiency of current public libraries can be increased on the basis of input and output. Therefore the commitment to increase the level of output to meet the current need shall continue by the amount, rather than by the commitment to reduce the level of input. Finally, the factors influencing the efficiency are the number of users, the physical environment, professional staffs, events planning, and electronic resources. After analyzing the five factors via multiple regression analysis, three factors such as the number of users, professional staff and events planning proved causal relationship with the efficiency.