In industry society, it is challenging to identify and prevent potential hazard factors since an industry is complex and changing variously. Particularly, as industrial accidents occur more frequently by secondary and tertiary indirect causes, rather than primary direct causes such as environmental changes or selfinduced disasters, it becomes more difficult to analyze the risk in safety management perspective. The purposes of this study are to reconsider the variable factors used in the existing Risk Priority Number (RPN) assessment method and to explore a new prioritization method for risks and disasters caused by various external environmental changes. To achieve this, various variables are considered including the currently used variables such as the occurrence frequency, the likelihood of occurrence, the severity. Among the variables, the eight key variables will be selected, and it is to take account of the relative weights between the variables.