A control section of a distribution apparatus decides whether data included in message has been stored by own DB or not, when distributing the message to an onboard apparatus based on transmitted information registered by second transmitted information table. From own DB, the control section of the distribution apparatus reads out data having been stored by the DB. For data that has not been stored by own DB, the control section of the distribution apparatus identifies another distribution apparatus having stored this data, and obtains this data from the identified another distribution apparatus. The control section of the distribution apparatus creates message including the data read out from own DB and the obtained data, and transmits the created message to an onboard apparatus which is a destination.