For the policy makers and managers as well as the workers at work, it is important to identify what affects, to what extent, the safety level and costs of work sites. Within this context, the author analyzes fifteen construction work sites of the Incheon International Airport from 1996 to 1999 and shows that the expenditures for safety personnel and education programs contribute to reducing industrial accident costs. In addition, the author demonstrates that the regression analysis out-performs Heinrich method in estimating the accident costs of those work sites.