Present status of Japanese wetland ecosystems and several trials towards rehabilitation and restoration of them are reviewed. Most of wetlands are altered to paddy fields and city areas, and natural wet lowland including tideland is the most endangered nature in Japan. Not only the preservation of natural wetlands but also the conservation of secondary nature of paddy field and waterways in traditional rural areas and restoration of original nature in city areas became the most concerned theme for nature conservation according to the national strategy for the biodiversity conservation. Not only the technological development based on the conservation ecology, but also the development of mitigation banking system are needed in Japan.