An Mw9.0 earthquake occurred in the Tohoku-oki area, Japan, at 14:46 local time on 11 March 2011. Tsunamis due to this earthquake were the largest in the recorded history of Japan and caused extensive damage to the eastern coast of Tohoku. In this study, a field survey of damage due to the extremely large tsunamis was carried out for 20 coastal areas along the Iwate and Miyagi Prefectures, focusing on damage to coastal structures and on whether these defense structures were broken completely or failed to perform some measure of tsunami protection. It was found that coastal structures failed locally, rather than entirely along a section of coastline. It is suggested that design conditions for coastal defense structures should be determined by taking into consideration topography, especially low-lying land areas behind structures.