Recently, research and development of autonomous driving technology has been actively conducted. In order to autonomous driving technology to be widely accepted by general users, sensory of security and comfortable behavior of vehicle is required. Therefore, this study aims to clarify the relationship between sensibility of occupant and brake operation during autonomous driving. Questionnaire surveys using real vehicle were conducted. From the result of using the average value, we could not show the feature about the brake operation. However, by classifying into groups using cluster analysis, the details of braking preference of each type were clarified.