A failure diagnosis apparatus for a vehicle enables communications between a gateway, which automatically and effectively collects information on a condition of a vehicle having a plurality of network buses, and an information center outside the vehicle in an automatic and efficient manner. A failure diagnosis section is mounted on the gateway installed on the vehicle. The vehicle-installed gateway has a connecting section for connection to information communications terminals such as portable telephones through wireless communications. In addition, the vehicle-installed gateway has a protection processing section for performing security processing on possession information possessed by the gateway.