Physical assistant robots are developed for daily living activities. However, the risk of fall is a major concern of physical assistant robots. In this study, we focus on curving motion, because fall is likely to occur during turning owing due to restricted degrees of freedom of joints. We developed new physical assistant robot, which could adjust the degree of freedom, and compared the curving motion. As a result, some subjects had a decrease in step length, when the hip rotation was restricted while curving. Additionally, the analysis of gait stability suggested that restriction affected the stability when they were curving.