This paper presents a master-slave type remote ultrasound diagnostic system. In the system, the motion of the master manipulator is controlled by a medical doctor and is reproduced by a slave manipulator carrying an ultrasound probe. The contact force between the probe and a patient is fed back to the master manipulator. High rigidity was achieved by adopting radius-guides in the slave manipulator. These allow precise position and orientation control of the ultrasound probe. In the master manipulator, a special mechanism keeps the orientation of the force sensor constant. The mechanism separates the functions determining the orientation and position of the probe. The control algorithm implements impedance control to reflect force, with the viscosity of the system varied depending on the measured force at the slave manipulator. Furthermore, a control strategy to enhance the safety of the system is proposed. Using the developed system, remote ultrasound diagnosis experiments through ISDN lines were successfully executed.