Electronic key system

An electronic key system installed in a vehicle, comprising:

• a first wireless communication controller performing transmission of a predetermined radio signal, as a verification signal, via a first wireless communication to confirm presence or absence of each of a first portable device and a second portable device each of which is usable as an electronic key of the vehicle;
• a second wireless communication controller periodically performing transmission/reception of a radio signal via second wireless communication to and from each of the first portable device and the second portable device upon transmitting/receiving the verification signal;
• and
• an integrity controller integrally controlling an operation of each of the first wireless communication controller and the second wireless communication controller, wherein
• when the first wireless communication controller attempts to transmit the verification signal to confirm presence or absence of the second portable device while the second wireless communication controller is periodically performing, as a first transmission/reception, transmission/reception of the radio signal with the first portable device via the second wireless communication in response to the first portable device receiving the verification signal,
• the integrity controller adjusts a transmission timing of the verification signal for confirming presence or absence of the second portable device to avoid overlapping between (i) a timing of a second transmission/reception that is periodic transmission/reception of the radio signal performed by the second wireless communication controller with the second portable device via the second wireless communication in response to the second portable device receiving the verification signal and (ii) a timing of the first transmission/reception that is being performed.