In the information society public libraries are situated in a rapidly changing social environment. Coming of post-printing era, expansion of knowledge, enhancement of social reflexivity, and growing flexibility of jobs, etc are bringing both crisis and opportunity to them. In order to take chances public libraries must collect materials in D/B format as well as printed and computer-file forms, and enlarge assistance to educational and research activities of residents and business firms. In addition, they must contribute to reducing information divide, increasing communal interactions, and providing leisure activities. It is required for them to develop a variety of programs and strengthen publicity among residents.