This study is focused on the mental pressure and the physiological index of users who are operating power mobility aids in barrier-free facilities. The purpose of the experiment was to investigate the impact of power mobility aids, barrier-free facilities and operating period for the physiological indexes of mental pressure. We tested the driving mission and the physiological index of 20 participants by using altered power mobility aids and barrier-free facilities in 8 different situations of the three operating periods. The results showed that the physiological indexes of mental pressure, such as galvanometric skin response and heart rate, had discriminative effects on the power mobility aids used. The mental pressure of operating on an elevator is higher than operating on a slope in barrier-free facilities. However there was no significant difference of mental pressure while the participants operated in the same type of barrier-free facilities.