VEHICLE ELECTRONIC KEY SYSTEM

A vehicle electronic key system includes a control device (14) mounted on a vehicle (100) and an electronic key (12) for transmitting a response signal (Sa) in response to reception of a request signal (Sr) from the control device (14). The control device (14) includes means for outputting a request signal (Sr) to the electronic key (12) in response to the ON operation of a main switch (62) of the vehicle (100) (request signal generation means (80), a transmission circuit (46), and a transmission antenna (72)), means for detecting a response signal (Sa) from the electronic key (12) (a reception circuit (44) and response signal matching means (82)), and means for performing an alarm output (monitoring means (84), a third drive circuit (56), and an alarm lamp (68)) when no response signal (Sa) is detected in spite of the output of the request signal (Sr).