A charging system comprising: an in-vehicle device to be mounted on a vehicle, the in-vehicle device having a writing unit that is configured to write data onto an IC card based on charge information, whereby the in-vehicle device has a function of charging a toll; a controller that is an external device and connected to the in-vehicle device via a serial line; a central system configured to wirelessly communicate with the controller, and to store charge location information, which indicates a location of a charging area of a toll-charging facility, and charge amount information, which indicates a charge amount at the toll-charging facility, wherein the controller comprises: a positioning processing unit that is configured to obtain positional information of the vehicle based on a global positioning system signal; a positional information storing unit that is configured to store the charge location information obtained from the central system; a toll information storing unit that is configured to store the charge amount information obtained from the central system; a passage determining unit that is configured to determine passage through a charge position by checking positional information of the vehicle obtained by the positioning processing unit against positional information stored in the positional information storing unit; a toll computing unit that is configured to compute a toll based on utilization of a toll-charging facility by the vehicle by checking information on the passage through the charge position determined by the passage determining unit against toll information stored in the toll information storing unit; and a charging processing unit that is configured to notify the toll computed by the toll computing unit to the in-vehicle device, and wherein the in-vehicle device is configured to charge a toll computed by the toll computing unit to the IC card. an in-vehicle device to be mounted on a vehicle, the in-vehicle device having a writing unit that is configured to write data onto an IC card based on charge information, whereby the in-vehicle device has a function of charging a toll; a controller that is an external device and connected to the in-vehicle device via a serial line; a central system configured to wirelessly communicate with the controller, and to store charge location information, which indicates a location of a charging area of a toll-charging facility, and charge amount information, which indicates a charge amount at the toll-charging facility, wherein the controller comprises: a positioning processing unit that is configured to obtain positional information of the vehicle based on a global positioning system signal; a positional information storing unit that is configured to store the charge location information obtained from the central system; a positioning processing unit that is configured to obtain positional information of the vehicle based on a global positioning system signal; a positional information storing unit that is configured to store the charge location information obtained from the central system; a toll information storing unit that is configured to store the charge amount information obtained from the central system; a passage determining unit that is configured to determine passage through a charge position by checking positional information of the vehicle obtained by the positioning processing unit against positional information stored in the positional information storing unit; a toll computing unit that is configured to compute a toll based on utilization of a toll-charging facility by the vehicle by checking information on the passage through the charge position determined by the passage determining unit against toll information stored in the toll information storing unit; and a charging processing unit that is configured to notify the toll computed by the toll computing unit to the in-vehicle device, and a passage determining unit that is configured to determine passage through a charge position by checking positional information of the vehicle obtained by the positioning processing unit against positional information stored in the positional information storing unit; a toll computing unit that is configured to compute a toll based on utilization of a toll-charging facility by the vehicle by checking information on the passage through the charge position determined by the passage determining unit against toll information stored in the toll information storing unit; and a charging processing unit that is configured to notify the toll computed by the toll computing unit to the in-vehicle device, and wherein the in-vehicle device is configured to charge a toll computed by the toll computing unit to the IC card.