抄録
We must reconsider the relationship between children's friend and their playground, in the age when it is difficult for children to make friends because of a decrease in number of children or increased lessons after school. The purpose of this study is to clarify the structure of children's groups and the relationship between the structure and playground, focusing individual situation. As a result, it was cleared that each child has different size of the structure of playing groups, and a small structure has tendency to contain particular groups, such as a group of only classmates or only brothers. A Positive correlation was found between the size of the structure of playing groups and the variation of playground they use. This correlation was based on not only the number of playing groups, but also the difference of a set of playgrounds used by one group. The difference of a set of playgrounds was caused by the character of playmates, the kind of playing activities they like, the location of playground, or equipment of playground.
