This paper examines an ideal way for consensus building of flood control projects for the local residents along the Ishikari River. The history of floods and flood control projects along the Ishikari River was examined to verify the efforts of the public administration and the local residents in consensus building for flood control projects from Meiji era until today. The results reveal a great difference between flood control projects and other infrastructure projects in consensus building. The primary reason for this difference comes from the purpose of flood control projects to secure the safety of lives and production against the natural disaster. A common recognition of this characteristic of flood control projects is essential for attempting an agreement on a project. JEL Classification: R58