A vehicle control system (100, 200, 300) comprising a plurality of on-board devices, wherein any one of the on-board devices is a specific on-board device and the specific on-board device includes: a first consistency information storage unit configured to prestore first consistency information including a permitted combination of versions of software of all the on-board devices that constitute the vehicle control system (100, 200, 300); a version acquisition unit configured to acquire versions of the software included in other on-board devices, the other on-board devices being the on-board devices other than the specific on-board device; and a first determination unit configured to determine, when the version acquisition unit acquires the versions of the software from the other on-board devices, whether or not the versions of the software of all the on-board devices that constitute the vehicle control system (100, 200, 300) are consistent, by comparing the version of the software of the specific on-board device and the versions of the software acquired from the other on-board devices with the first consistency information, characterized in that the version acquisition unit is configured to acquire the versions of the software included in the other on-board devices when a power source of a vehicle is turned on, the specific on-board device further includes: a first transmission unit configured to transmit, when the first determination unit determines that the versions of the software of all the on-board devices that constitute the vehicle control system (100, 200, 300) are inconsistent, version information including the versions of the software of all the on-board devices that constitute the vehicle control system (100, 200, 300) to an external server; and a reception unit configured to receive, from the external server, determination result information that is information on a determination result determined by the external server based on the version information transmitted by the first transmission unit, the determination result information indicating whether or not the versions of the software of all the on-board devices that constitute the vehicle control system (100, 200, 300) are consistent. a first consistency information storage unit configured to prestore first consistency information including a permitted combination of versions of software of all the on-board devices that constitute the vehicle control system (100, 200, 300); a version acquisition unit configured to acquire versions of the software included in other on-board devices, the other on-board devices being the on-board devices other than the specific on-board device; and a first determination unit configured to determine, when the version acquisition unit acquires the versions of the software from the other on-board devices, whether or not the versions of the software of all the on-board devices that constitute the vehicle control system (100, 200, 300) are consistent, by comparing the version of the software of the specific on-board device and the versions of the software acquired from the other on-board devices with the first consistency information, characterized in that the version acquisition unit is configured to acquire the versions of the software included in the other on-board devices when a power source of a vehicle is turned on, the specific on-board device further includes: a first transmission unit configured to transmit, when the first determination unit determines that the versions of the software of all the on-board devices that constitute the vehicle control system (100, 200, 300) are inconsistent, version information including the versions of the software of all the on-board devices that constitute the vehicle control system (100, 200, 300) to an external server; and a reception unit configured to receive, from the external server, determination result information that is information on a determination result determined by the external server based on the version information transmitted by the first transmission unit, the determination result information indicating whether or not the versions of the software of all the on-board devices that constitute the vehicle control system (100, 200, 300) are consistent. a first transmission unit configured to transmit, when the first determination unit determines that the versions of the software of all the on-board devices that constitute the vehicle control system (100, 200, 300) are inconsistent, version information including the versions of the software of all the on-board devices that constitute the vehicle control system (100, 200, 300) to an external server; and a reception unit configured to receive, from the external server, determination result information that is information on a determination result determined by the external server based on the version information transmitted by the first transmission unit, the determination result information indicating whether or not the versions of the software of all the on-board devices that constitute the vehicle control system (100, 200, 300) are consistent.