Abstract
According to the Automobile Damage Compensation Security Act (1955) in Japan, an operator (usually owner) of an automobile is liable for damages of bodily injury caused by automobile accidents, if he cannot prove that he and the driver of his automobile was not negligent. On the other hand, the rule of comparative negligence applies to damages by automobile accidents. Therefore, it is a legal problem if an injured person be negligent and is subject to reduction of damages when he does not wear a seat belt. To wear a seat belt is not a legal duty at present, so that there is a problem if an injured person be deemed negligent for not wearing a seat belt, and if the comparative negligence rule is applied to him.