The Osaka bay is one of the typical enclosed seas in Japan. “The action plan to regeneration of Osaka bay” was enacted in 2004 for the environmental improvement by the Promotion Committee of Osaka bay regeneration which is composed with government bodies and related municipalities. Adaptive management has been facilitated for the implementation of the plan. Enhancement of public-private partnership and development of environmental countermeasures are twofold major issues in the management. Some related activities are introduced as case studies.