<p>　The areas affected by the Great East Japan Earthquake of 2011 saw much residential mobility, causing a transformation of the urban areas.　This study clarified the relationship between the reorganization of affected urban areas and the residential mobility in the affected prefectures of the Tohoku region.　We analyzed characteristics of the prefectures by comparing national census data in 2010 with in 2015.　The results are summarized as follows:</p><p>　Changes in the regional structure and residential mobility are related to each other.　Although this relationship affects the disaster-stricken areas, the mobility that occurs due to disasters is caused by unexpected physical and psychological damages.　The movements must be determined in a short span of time with uncertain information, thereby being easily influenced by vague regional images and reputation, and taking the form of a collective mobility by the group with high anxiety.　Similarly, in the case of the Great East Japan Earthquake, many movers decided to shift to a new address in their own municipalities or neighboring municipalities that were not far from the previous residence.</p><p>　Among the affected prefectures of the Tohoku region, Iwate Prefecture, especially, saw many such movements.　The inhabitants had formed a small living area in a narrow plain on the coast.　Spatially, its area was not very contiguous with other living areas formed in the neighboring municipalities.　Therefore, in some municipalities, more than 60% of inhabitants who moved after the earthquake selected a new address within their own municipality.　As a result, corresponding to city planning with respect to disaster prevention, the shape of the urban area was transformed toward the inland direction.　In Miyagi Prefecture, in addition to moving within the daily living area, mobility to Sendai City dominated, which is the prime city in the Tohoku region. Miyagi Prefecture’s disaster-stricken areas have higher population density than Iwate Prefecture’s.　Small- and medium-sized municipalities in Miyagi alone could not have kept up with the rapidly increasing demand for housing.　As a result, people who did not get a new residence in the previous neighborhood showed preference for Sendai, which has plenty of available housing.　On the other hand, in Fukushima Prefecture, the rise and fall in the population due to the nuclear accident was remarkable;the mobility observed there greatly went beyond the daily living area.　This is because those movements occurred on the basis of evacuation orders and impacts on health.　In some towns and villages where the whole population was evacuated, the urban area itself disappeared for several months to several years.</p>