PROBLEM TO BE SOLVED : To provide an objective and quantitative risk analysis method of whole system capable of achieving balanced design between risk and cost. SOLUTION : A risk analysis device comprises : an operation part 104 configured to create a failure mode scenario tree which is an event tree from breakdown of components of equipment system to equipment facility hazard using facility design information 101 of the facility system and a facility function hazard master 102 indicating degradation of basic function and to calculate the occurrence frequency as a risk index using the tree structure; an operation part 105 configured to create a risk scenario tree which is an event tree from facility function hazard to quality risk and to calculate an indicator value indicating the severity using the tree structure; and a risk level determination part 108 configured to plot the calculated occurrence frequency and the severity on a risk matrix and to determine the risk level 109 of the facility function hazard. SELECTED DRAWING : Figure 1 COPYRIGHT : (C)2019, JPO&INPIT