In recent trend, the space for children is changed from residence to various place for children, such as education, cultural, and play facilities, and is gradually expanded comparing to the past. The environment where children's ability and creativity can be manifested and they can keep sound body and mind, should be provided in architectural space for children. Considering children, therefore, is required in the process of environmental design and its management. To find out children's space usage behavior according to space type and physical elements, in this study, Classified those spaces based on the feature of area with checklist, and observed physical elements by each reading room. Also, marked user's data on the plane prepared in advance, while staying each room for an hour. Clarifying the relationship between space type and physical elements by using this data, I intend to propose proper space organizing elements and its organizing method for children's library.