An economy running system having: a function of stopping an internal
combustion engine of a vehicle when the vehicle stops and all of stop
conditions are satisfied; and a function of restarting the internal
combustion engine of the vehicle. The economy running system includes: a
control unit that judges whether the vehicle stops or not, and judges
whether each of the stop conditions is satisfied or not; and a
notification unit. When the control unit judges that the vehicle stops
and that at least one of the stop conditions is not satisfied, the
control unit causes the notification unit to notify to a user first
notification information concerned with the at least one of the stop
conditions.