Railway is a huge traffic system which is operated organically combining all the elements: vehicle, track, electric power, signal/communication, operation, etc. Safety level has been improved steadily by learning lessons from past accidents. But with rapid progress in high-speed, massive, high-frequency transit fresh idea of accident prevention is now in order. In quest of effective and efficient countermeasure, we aim to establish an adequate safety evaluation/management method. Our proposals are basic concept relating to safety, analysis of fatal accidents, quantitative safety evaluation through maltivariate analysis, risk assessment and comprehensive index, and human error diagnosis. Based on these method, we developed a safety management supporting system.