The identity of public libraries in Japan is a social education institution under the ｢Social Education Act｣ and the ｢Library Act｣. For these identities, the local government’s board of education has operated and managed public libraries, and some have managed by the Management Outsourcing System to public organizations. Then, in 2003, the ｢Local Autonomy Act｣ was revised to introduce the Designated Manager System in form of administrative disposition, and expanded the scope of application to private institutions and organizations. As of the end of 2018, 18.0% of public libraries introduced the DMS, but the pros and cons surrounding it are sharply opposed. This study outlined the overall status of the DMS and the introduction of public libraries, and critically reviewed major issues. As a result, As a result, there was much controversy over the expected cost reduction, service improvement, employee professionalism, business continuity, and cooperation network establishment when DMS was introduced. The reasons were due to downsizing-based personnel management, contract-oriented employment, short periods of designation, lack of multiple competitive markets, and declining service capabilities of irregular workers. The public library is a knowledge and cultural infrastructure that enhances human values and social dignity based on faithful collection and active service, and is a local public goods that emphasizes non-exclusion and non-competitiveness. Given the increasing number of cases in which public libraries are recently contracting out to cultural foundations in Korea, DMS is not a fire across the river. We need to be wary of the possibility that Japan’s unbearable institutional lightness will be applied to public libraries in Korea.