Abstract: In this study, older male drivers' stress while driving in straight links and while proceeding through intersections is investigated. Controller area network (CAN), self-reported stress (SRS), and physiological data was collected in 22.4 km-long experimental trips among older and young drivers. First, this study finds that older drivers reported much less stress than young drivers. However, principal components (PCs) of the physiological data demonstrate that older drivers might underrate their driving stress in entire trips, except regarding turning at intersections. Moreover, following other vehicles reduced older drivers' driving stress because preceding vehicles might help them control driving speed, detect the path, and prevent road risks. In contrast, the similar condition increased the stress level of young drivers. The results of random effects regression models confirm that age was the significant impact factor on SRS and physiological data. While examining whether the stress at intersections could affect their driving behaviors, significant difference between two age groups was found neither in turning time nor in the driving speed. This study also confirms that physical and mental changes with aging can negatively affect older adults' behaviors. Considering the relationships among stress, speed, and accidents, we suggest the provision of more driver assistance systems, training, and education and improving intersection design for older drivers.