An on-vehicle breakdown-warning report system is disclosed. an occurrence of break-down is detected and judged based on a signal in an electronic control system installed on a control apparatus for an engine ignition system, a charging system, an engine fuel system, a engine cooling system, a power transmission system, and an oil lubricating system of an automobile or a diagnosis display system; and a diagnostic data is sent to an information terminal device of a diagnosis and maintenance agency or a service company having a diagnosis and maintenance agency as a contents information by using an on-vehicle mobile communication apparatus, and an action for an emergency measures and a maintenance schedule is asked.