In this study, we evaluated the mental stress due to corner entry speed while riding a mobility scooter by measuring skin conductance. A mobility scooter is a four-wheel electric wheelchair with a steering bar-handle. These scooters, known as 'senior cars' in Japan, are generally sold for use by elderly people. Some of these scooters have a system that automatically reduces their speed to approximately 70% of the maximum depending on the steering angle at corners. However, because of mismatch with the intention of the driver, the preset deceleration rate may be uncomfortable for the driver. With the objective of providing appropriate assistance without any discomfort in such circumstances, we evaluated the mental stress of the driver. Skin conductance (SC) is one index for measuring mental sweating related to sympathetic nerve activity. First, we modified a commercially available mobility scooter for use as an experimental scooter such that it can be controlled using an external personal computer. Then, we measured SC in a task that involved turning right into a corner at a constant speed using the experimental scooter, and evaluated the mental stress due to the corner entry speed. A positive correlation between the amplitude of SC and entry speed was obtained. Further, the results of a questionnaire used to evaluate the ride discomfort after each experimental task indicated that 'No Fear' and 'Safety' decreased as the speed increased. As these results are consistent with the measurement results of the SC amplitude, we concluded that fear due to corner entry speed can be evaluated using SC.