The data of accidents in the elementary schools in the ward areas of Tokyo, urban districts of Tokyo were linked with the penetration rate of lawned schoolyard of relevant areas in order to research the relation between accidents occurring at elementary schools and the lawn laying conditions. The data of accidents of elementary schools were obtained from the NAASH (National Agency for the Advancement of Sports and Health), and the period of analysis was set as 5 years from 2005 to 2009. The data of penetration rate of lawned schoolyard of relevant areas were obtained with questionnaire survey. While the penetration rate of lawned schoolyard of elementary schools in Tokyo metropolitan area was elevated from 2005 to 2009, the accident rate occurred on schoolyards in relevant area was decreased. The school accidents especially occurred during physical education, cocurricular sports club activity, and school events such as field day were significantly decreased. Considering sorts of injury, the school accidents of incised wound and sprain were significantly decreased. It was found that the accident rate in schoolyard was decreased especially under cool condition of 2-8 ℃ and moderate condition of 18-24 ℃. Lawn laying might have significant effects on diminution of accidents occurred on schoolyard.
