In this paper, we develop an intelligent walking support machine with the safety devices, which provide a patient with partial body weight support and prevent the patient from fulling. The constant force springs are used in order to provide the patient with partial body weight support. The powder brake, which can control the torque, is used as the device to prevent patient's falling. We propose a new control method to prevent patient's falling When a patient normally uses this support machine, the machine provides the patient with partial body weight support. After the machine detected the patient's full, the machine prevents the fall by applying the impedance control to the powder brake. The usefulness of the walking support machine is experimentally examined.