Public library have been changing with the change of lending system. In recent years, many documents have been put into digital form, and then the argument that library is unnecessary arose. In response to this controversy, another argument about the meaning of library arose too. Nowadays, the movement that reconsider library as a "Third place." is also seen. "Third place" means public space coming after home and workplace. In this way, architectural planning of public library, particularly in browsing space, have been changing to be designed as a place of relief gradually, and new libraries called "stay-type library" have been built recently. Therefore, this study aims to reveal the relations between visitors' behavior and spatial structure of public library in order to design better library for staying. This study examines Yamanashi prefectural library. We recorded visitors' movement paths on maps by tracking visitors and recorded visitors' distribution by taking movies. We investigates the correlation between visitors' movement, staying activity and spatial characteristics analysed by space syntax theory. Space syntax values were calculated by convex analysis, Isovist, and Visibility Graph Analysis (VGA). Through these analyses, four points are revealed: 1. Correlation between visitors' movement path and spatial indices calculated by space syntax analysis, 2. Seat selection preference between the types of activity, 3. Correlation between the seat occupancy rates divided by the type of activity and values calculated by space syntax analysis, 4. Differences of spatial configuration indices between the types of activity.