The purpose of this study is to examine the improvement of the slipperiness of building floors and to test the safety in accidental collision in the primary schools. To perform this purpose effectively, the actual 20,202 cases of accident on the year 2000-2009 which had been dealt by Seoul School Safety and Insurance Association were analysed in several aspects. And to test the current slipperiness and hardness of building floors, 3 primary schools whose construction year differed were examined. This study found that among the indoor accidents of 2,646 cases on the year 2000-2002, 70.7% accidents of them were caused by slipperiness. It was also found that the building floors of the primary schools could not be safe from the result of examining the slipperiness and hardness of the building floors. As the result of this study, it showed that the desirable efficient criterion of slipperiness would be more than C.S.R 0.4, and that of safety in accidental collision would be less than Gs 100G for the safety of primary school students.