Although prior researches have been investigated the impact of insured cost(direct cost) on employers and employees, little work has attempted to categorize the items of unsecured cost(indirect cost) by accidents. On this basis, the goal of this study was to achieve a better understanding of the nature of accident cost of unsecured cost. Specifically, this study aimed to categorize the unsecured cost items according to the domestic industry circumstances and use these results for a basis of other accident cost related studies. The results of this study are as follows: (1) accident development steps were categorized as twelve items for improved management according to each step of accident development (2) the points of occurrence and termination of the unsecured cost were identified for the improved management according to each step of accident development and (3) characteristics of each item in unsecured cost were studied and identified for a better control of accident costs. These results provide a basis for further researches on the unsecured cost.