In this knowledge-based society of this age, librarianship takes a professional position and requires essential principles of ethics that has to be observed. Therefore, library associations and professional communities all over the world have released criteria and code of ethics to make their professional positions to keep. This research investigated and analyzed the codes of ethics for librarians in United States, Great Britain, Japan, and South Korea which are based on the mission of each library of each country. Based on these analysis and comparison, this research proposed more advanced codes of ethics for South Korea. The proposed model of codes of ethics consists of two parts: ethics for information and ethics for professional positions. The ethics for information contains six essential elements: equal access and services for information, denial of inspection, protection of privacy, neutralization of librarian, and security of intellectual freedom. The ethics for professional positions consists of 8 essential aspects: exclusion of personal benefit, continuous efforts for developing knowledge, keep the professional position, conflicts between professional task and organization, relationship with co-workers, ensure the conditions of rights and welfare for employees, cooperations among libraries, and contribution for creation of new culture.