For reducing traffic accidents by aged drivers, researches on active and passive safety technologies and driver characteristics have been carried out. However, several research achievements are little effective for aged drivers since the characteristics of aged drivers are distinguished from normal drivers and difficult to analyze. In order to clarify the distinguished factor of aged drivers, this report is based on the assumption that aged driver characteristics are related to both their life style and physical characteristics. The driver characteristics, the life style, the physical characteristics are investigated from several questionnaire surveys followed by experiments using driving simulator, and actual driving test. The evaluation method of aged drivers' driving performance is proposed based on life style and physical characteristics, and this method provides useful suggestions for understanding the aged drivers' driving characteristics.