‘Neopolis’ was a series of development of detached housing estates by a prefabricated housing company since the 1960’s. This study conducted a questionnaire survey in ‘Midorigaoka Neopolis’ as one of the oldest and largest ‘Neopolis’ estates, and examined the transformation of the dwellings and families through time. The survey especially focused on the change of the site/building size, the reason for renovating/rebuilding, and the deciding factor of estate/dwelling selection. It was concluded that cultivating renovation market is one of the key issues for the estate as an old new town.