During these fifteen years, Japanese housing policy has changed a lot. Design to prepare for the residents' ageing has been the most crucial issue. In 1986, the forecast of Japanese population ageing indicated that Japan will have almost a quarter of persons aged 65 and over in the years to come. To prepare for the future, the government started to redefine the direction of policy to house the senior citizens (Kose & Nakaohji, 1991). In 1991, design guidelines for the public rental housing were introduced, and in 1995 the concept of guidelines was expanded to cover every dwelling with the issuance of a circular from the Director- General of the Housing Bureau of the Ministry of Construction. The fundamental ideas were subsequently adopted as the requirements for government subsidized housing mortgages in 1996. It succeeded in accelerating the change of dwelling design in Japan (Kose, 1996; Kose, 1997a; Kose, 1997b; Kose, 2001b). It is to be noted that in several countries design guidelines or requirements have been targeted to make dwellings livable for seniors and people with disabilities, but very few introduced economic incentives to realize such targets. Currently, in the UK and in some States or cities of the USA, visitability requirements are in force or under discussion.