Librarians long ago proclaimed themselves professionals. Until recently, however, librarians and information professionals gave very little thought to professional ethics, which have corne to play an increasingly important role in all areas in modern society. They have been stimulated to consider their specific domain within an ethical context now. Professional norms express obligations which include prescribing standards, principles of responsibilities, and rules of duties. Professional codes attempt to formulate the norms of professional ethics and are the basis for disciplinary measures of various kinds. This paper discusses professional properties and characteristics of libarianship with a special reference to the code of professional ethics. The codes of ethics of the American Library Association, the Library Association, and of the Japanese Library Association have been reviewed and compared. The arguments on the enforcibility of the professional codes of ethics, therefore, on their effectiveness have been discussed. Author concludes that, despite some doubts on the practical effectiveness of the ethics code expressed by a number of scholars, a code of ethics is very much required in the information professions. Properly disseminated, a code would enhance the status and standing of the profession by demonstrating concerns for the maintenance of the highest possible level of standards of professional services. It would also play an important role in raising consciousness of the clients by communicating the value of the works.