This paper presents the outline of post investigation on damage to buildings by EF5 tornado in Iowa, U.S. on May 2008. The transient wind speed in Parkersburg, which was estimated by applying DOD index defined in enhanced Fujita scale to the state of buildings suffered damage, was compared with wind speed based on engineering model. The characteristics of each wind speed distribution resulted in well consistent. With respect to the post disaster activity, the authors carried out field investigation in Parkersburg for the acquisition of recovery process of buildings suffered damage for four months after the disaster. Through the investigation, it made clear that the recovery ratio of damaged residences depends on the degree of structural damage. Finally, the recovery process of damaged buildings was summarized along with the process related to emergency actions such as response, recovery and mitigation taken by federal and state governments.