A driving assistance systems, methods, and programs are capable of communicating with a route guidance system that searches for a planned travel route of a vehicle and provides guidance on the planned travel route. The systems, methods, and programs accept, as input, the planned travel route from the route guidance system as a route for driving assistance and provide driving assistance of the vehicle on the route for driving assistance. The systems, methods, and programs accept, as input, when the planned travel route whose guidance is provided by the route guidance system no longer matches the route for driving assistance, the planned travel route from the route guidance system.