A vehicle electronic key system includes a plurality of in-vehicle communication devices and an authentication device. Each of the plurality of in-vehicle communication devices communicates wirelessly with another in-vehicle communication device, and based on a signal transmitted from the another in-vehicle communication device, generate distance-related information that directly or indirectly indicates a distance to the another in-vehicle communication device. The authentication device specify a plurality of inter-communication device distances based on the distance-related information generated by the plurality of in-vehicle communication devices, and does not execute a vehicle control when at least one of the plurality of inter-communication device distances deviates from a predetermined normal range.