To provide a fraudulent running prevention system by which tampering of an accumulated running distance of a vehicle can be prevented with more certainty.

In a fraudulent running prevention system 1, an MPU 31a determines whether or not a running distance of a vehicle can be accumulated by determining whether or not power is supplied from a battery 40. If the running distance of the vehicle is determined to be accumulated, a meter ECU 31 transmits an in-vehicle meter connection confirmation signal to an engine ECU 20, and, if the running distance of the vehicle is not accumulated, the meter ECU 31 does not transmit any in-vehicle meter connection confirmation signal to the engine ECU 20. Then, if the engine ECU 20 has received the in-vehicle meter connection confirmation signal, the engine ECU 20 allows an in-vehicle engine 10 to start or the vehicle to run. If the engine ECU 20 has not received any in-vehicle meter connection confirmation signal, the engine ECU 20 does not allow the in-vehicle engine 10 to start, that is, does not allow the vehicle to run.