In present-day Japan, many people do not choose traditional style of houses and housing landscapes are therefore changing, but the mechanism of this process has not been sufficiently studied. The purpose of this study is to clarify the function of the builders in the formation of housing landscapes. I researched on the outward appearance of houses and interviewed builders involved in housing development in Higashi-Hiroshima City, Hiroshima Prefecture. The results show that the builders have opportunities to decide whether to establish building agreements and to build ready-for-sale houses or customized houses under housing development. This would allow them to control the development of fundamental housing landscapes; however, this is a superficial system. To maintain or develop housing landscapes, residents should have a sense of ownership and intervene actively in the mechanism.