We have proposed a passive-type walking support system equipped with a lift device. The lift device has a constant force spring and a powder brake. The constant force spring is used in order to provide a patient with partial body weight support. The powder brake is used in order to prevent the patient from falling down. This walking support system is intrinsically safe, because this system consists of only passive components with no active actuators. The system normally provides the patient with partial body weight support. If the patient is likely to fall down, the system prevents the fall by applying impedance control to the powder brake. In this paper, we discuss the effectiveness of the impedance control from simulation results and experimental results.