This study aims to clarify the relationship between the buildings and the attached rooftop green space from the viewpoint of degree of openness, and the chronological characteristics. Some 1,304 rooftop green spaces developed by 2020 were collected from monthly magazine "Shin-Kenchiku (New Architecture)" and specialized books and classified into three categories of openness such as full open, limited open and closed to the public, and cross tabulation of the indicators including the location, the establisher, the presence or absence of staying and attracting facilities, the shape and components of the rooftop green space in each category was performed. As a results, the rooftop green spaces developed by public institution and those for attracting visitors were more open, staying facilities were more limited open. Besides, the number of plant species and its combination has increased since the 1990s and the spaces became as of a garden in the rooftop green spaces fully opened while lawn plantings have increased in the closed rooftop green spaces. On the other hand, limited rooftop green space has increased since 2000s with installation on the highest floors and a combination between plantings.
