A stationary steering operation determination means determines whether or not stationary steering operation is being performed repeatedly at a determination cycle period that is set to be longer than a cycle period at which a certain signal is detected. And a stationary steering operation determination means makes a decision as to whether or not stationary steering operation is being performed, on the basis of vehicle speed as detected by a vehicle speed detection means and steering angle as detected by a steering angle detection means. If it has been determined that stationary steering operation is being performed, a steering sensitivity alteration means decreases the steering sensitivity by reducing a pilot pressure or the like. And a notification means notifies the operator that stationary steering operation is being performed.
