Keyless entry system using communication via human body

A keyless entry system, comprising:

• a detector that detects a person's action of getting off a vehicle;
• a portable device including a portable device controller that perform communication of a signal for authentication and a portable device electrode that induces an electric field in a human body by the signal;
• and
• a vehicle side device provided in the vehicle, in communication with the portable device, and including:
• a vehicle-side electrode that is disposed inside the vehicle and in a position where the vehicle-side electrode is communicable with the portable device via a human body at the time of a person's preliminary action of getting off the vehicle, and that detects the electric field, wherein the person's preliminary action is followed by the person's action in getting off the vehicle, and
• a vehicle-side controller that has a signal input thereto by the electric field and that authenticates the signal, and
• wherein when the detector detects the person's preliminary action of getting off the vehicle, the vehicle-side controller determines that the portable device has been left in the vehicle if the vehicle-side controller has no history of authentication of the portable device, or if the vehicle-side controller cannot perform authentication of the portable device therewith, immediately after the detection by the detector, and
• wherein the vehicle-side device further includes a device provided in the vehicle, the vehicle-side controller making the device perform a notification operation based on the determination that the portable device has been left in the vehicle.