Unfortunately it is a common experience in our society that a set of rules introduced as a part of safety management system fails to prevent a tragic accident from occurring. The causes of such failures can be classified according to what features of each system are regarded as having relevancy to the accident occurred .In this paper I discuss how to learn appropriate lessons from failures showing some examples of the accidents that occurred recently in Japan. In the course of the discussion, some lessons are discarded as inappropriate. The lessons learned are used to clarify what problems we have to be faced with in controlling human behavior with safety management rules.
