To generate a damping force in a steering damper only upon an unintentionally caused handle action when it is truly necessary to restrain the turning of the handle, according to whether the cause of a handle action is intentional or unintentional. A rotation type steering damper is provided coaxially with a steering shaft, and the generation of a damping force or zero damping force is selected through a changeover by a variable valve provided in a bypass passage for communication between a right liquid chamber and a left liquid chamber of the steering damper. The changeover is controlled by a control device, which functions based on the direction of a moment exerted on the steering shaft detected by a moment sensor and the magnitude and direction of a rotational angular velocity concerning the turning of the steering shaft detected by a rotational angular velocity sensor, for controlling a damping force that is generated only when an unintentionally caused handle turning action opposite in direction to the moment is present and the rotational angular velocity has exceeded a predetermined threshold value.