KEYLESS ENTRY DEVICE

A portable device (3) acquires a signal of noise component data that is based on signal intensity of a signal received in an OFF time in which the portable device (3) does not communicate with a vehicle-side device (2), and then transmits an information signal that is based on the noise component data, and the vehicle-side device (2) transmits a measurement signal controlled based on the information signal, at a predetermined time period.