Group living (GL) for people suffered from dementia jn Japan is getting more popular after the introduction of public care insurance in 2000. However, the quality of living and care environment is not yet satisfactory enough. The purpose of this paper is to clarify the environmental factors influencing upon people's behaviors in group livings in order to evaluate the quality of GL. Eleven GLs in Finland were selected as survey fields and behavior and the setting of all residents were recorded by observation. The main results are abstracted as follows: (1) Differences of spatial features and residents' activity or dementia condition influencing upon the each GL's character. (2) Residents' lives and behaviors were affected strongly by their ability of moving, dementia level and staffs way of support. (3) Most of residents's activities occurred in the area between their private room and main living area where attached to dining room. (4) Ideal size of the group might be 8 to 9 people in the context of communication. (5) The differences of the extent of dementia affect the communication between residents, and staffs relation to the residents must be fully considered the situation of the group. (6) Each factor in the environment related each other and influenced the lives of residents and staffs. So when evaluate the environment of GL, it is necessary to see their lives from not only surface factors but also the substantial viewpoint, lives and behaviors.