A center device, comprising: a distribution control unit that is configured to control distribution of data to a vehicle via a communication network, said vehicle including an electronic control unit as a target for a program update and a vehicle master device that is configured to distribute data for the program update to the electronic control unit a normal operation determination unit that is configured to determine whether operation of distributed data on a vehicle is normal based on information received from the vehicle; and a distribution target expansion unit that is configured to expand a distribution target for the data when the normal operation determination unit determines that operation of the distributed data on the vehicle is normal after the data was distributed to the vehicle; characterized by the distribution target expansion unit is configured to expand the data distribution target for the data by causing the vehicle master device to expand a function or performance of the distributed data, the distribution target expansion unit is configured to cause the vehicle master device to expand the function or performance of the distributed data by transmitting, to the vehicle for which the function or performance of the distributed data has not been expanded, a command for instructing the vehicle master device to expand the function or performance of the distributed data when the normal operation determination unit determines that the operation of the distributed data is normal, and the distribution target expansion unit is configured to not transmit the command for instructing the vehicle master device to expand the function or performance when the normal operation determination unit determines that the operation of the distributed data is not normal. a distribution control unit that is configured to control distribution of data to a vehicle via a communication network, said vehicle including an electronic control unit as a target for a program update and a vehicle master device that is configured to distribute data for the program update to the electronic control unit a normal operation determination unit that is configured to determine whether operation of distributed data on a vehicle is normal based on information received from the vehicle; and a distribution target expansion unit that is configured to expand a distribution target for the data when the normal operation determination unit determines that operation of the distributed data on the vehicle is normal after the data was distributed to the vehicle; characterized by the distribution target expansion unit is configured to expand the data distribution target for the data by causing the vehicle master device to expand a function or performance of the distributed data, the distribution target expansion unit is configured to cause the vehicle master device to expand the function or performance of the distributed data by transmitting, to the vehicle for which the function or performance of the distributed data has not been expanded, a command for instructing the vehicle master device to expand the function or performance of the distributed data when the normal operation determination unit determines that the operation of the distributed data is normal, and the distribution target expansion unit is configured to not transmit the command for instructing the vehicle master device to expand the function or performance when the normal operation determination unit determines that the operation of the distributed data is not normal.