To postpone the time of replacing a battery of a portable machine.

An immobilizer ECU 15 transmits a transmission password code taking an electromagnetic wave as a medium from a coil 13 (step 110). In the portable machine 20, when a transponder circuit 21 receives a transmission password code through a coil 22 (step 200), the feedback password code is transmitted from the coil 22 taking the electromagnetic wave as a medium (step 220). The immobilizer ECU 15 receives the feedback password code through the coil 13 (step 130), and when the feedback password code and the registration code match, an engine ECU 16 is permitted to start the engine (step 140). The immobilizer ECU 15 transmits power taking the electromagnetic wave as a medium from the coil 13. The coil 23 of the portable machine 20 receives the power taking the electromagnetic wave as a medium, and outputs the power to a secondary battery 25 to a diode D1.