The purpose of this study is to clear the relation between the visual unity and the volume of the parallel two buildings space. We made the experiments, using the space simulator which enable us to observe scale models from eye level. Then we got the quantitative data of the factors of visual unity, such as the height, the length and the distance of the buildings. After analysing them, we came to the conclusions that the visual unity of space was greatly influenced by the height than the length, and the distance could be estimated by the height and the length.
