There are some safety assessment, some of them are inherent safety and probabilistic safety assessment. But, it has not clearly defined of them. This paper reports the difference of both safeties and the way of realizing optimization of Life Cycle Cost of Safety Related System. And it proposes the concept of Safety Cost and reports it on the Railway transmission systems. About the railway systems, the cost loss is fewer than the more safety transportation facilities in signaling systems. So it is important to identify the concepts of the inherent safety and the Safety Cost must need to validate it by the Risk Assessment.