VEHICLE DIAGNOSTIC SYSTEM AND MOBILE BODY DIAGNOSTIC SYSTEM

A vehicle diagnostic system includes: a vehicle diagnostic device including a communication unit that communicates with a vehicle which drives autonomously, and a diagnostic unit that performs, via the communication unit, diagnosis as to whether the vehicle is being hacked; and electrical apparatuses that communicate with the vehicle diagnostic device via a network. The diagnostic unit performs the diagnosis when an operational state of at least one electrical apparatus among the electrical apparatuses changes.