The purpose of this study is to clarify the process of constructing new government buildings in consideration of tsunami inundation and urban development after the construction of new government buildings in Kainan, Gobo, and Tanabe cities in Wakayama Prefecture, which are expected to be damaged by the giant Nankai Trough earthquake. The process of building new government buildings was clarified through interview surveys of each city, and the content of plans and other measures formulated by the administration for urban development after building new government buildings were ascertained through interview surveys and close reading of publicly available plans. As a result, the three municipalities with different patterns of new construction of government buildings showed differences in the planning methods, contents of the plans, and measures for the central city after the construction of new government buildings.