For improvement of authorization standard of long-life quality housing, this paper aim to propose an evaluation method of flexibility and variability of dwelling unit division in case of apartment building. Firstly, we show a concept called“skeleton space”and then propose an evaluation method to secure flexibility and variability of floor area and configuration of dwelling unit division from the viewpoint of height，floor area and frontage of skeleton space. Secondly, we consider and indicate some consideration matters in the design and legal consideration matters to realize the change of floor area and configuration of dwelling unit division.
