Since the motor vehicle is controlled by the driver, dynamic consideration of the driver-vehicle system is necessary. In this sytem, eye sight is the most important sense with which the driver gets information from the course. In the present research, first, sighting distance in steady straight running was measured by the “slit method”. Next, sighting distance and sighting angle in various curvilinear runnings were measured by use of a “sight point camera” devised by the authors. Introducing the conception of sighting distance and sighting angle, dynamics of the driver-vehicle system is contrived. Theoretical calculation showed that sighting distance should be longer than a certain critical value to make the system stable.