Distracted driving represented 23% in 1995 and 21% in 1994 of the number of fatal traffic accidents caused by vehicle drivers1) . It was the leading cause of fatal traffic accidents in Japan in 1995 (2129 accidents) and was second only to speeding as a cause of fatal traffic accidents in 1994. Speeding is traffic violation most responsible for fatal accidents through the teens and the 20s, but in general decreases with age. The percentage of the accidents caused by distracted driving increases with age, and it becomes the highest percentage beginning in the 30s. Avoidance of distracted driving is thought to become more important for preventing traffic accidents, especially fatal accidents, as the percentage of older drivers increases. Distracted driving can easily be overlooked if it does not cause an accident. Most drivers are not aware that they commit the violation of distracted driving. Also, there are various behaviors of drivers which cause distracted driving. Therefore causes of distracted driving were examined, and they were classified into 3 main groups. Then each group was examined to find out what the drivers should do to prevent the accidents. In the first group, a specific action was the cause of distracted driving, so the frequency and the Safety in Action 25-28 February 1998 2 each subjective risk of specific action was examined by a questionnaire. In the latter 2 groups, it was difficult to control the cause of distracted driving, so the effect of lowering velocity to prevent the accidents was examined. The examination was based on the accident reports by police officers.