To eliminate error decision on a start/stop of an engine so as to smoothly start the engine by means of remote control by measuring a generation voltage of an alternator every predetermined time and deciding a start/stop of the engine on the basis of the generation voltages, which are obtained serially predetermined times, of the alternator.

When an instruction to start an engine is inputted to a controller 12 provided with a CPU 10, a counter 16, and a timer 14, the controller 12 gives an engine starting unit 20 an instruction to start the engine 3. The engine starting unit 20 turns on an ignition switch 21 so as to rotate a starter motor 23, so that an alternator 1 is driven by the rotation of the engine 3 via a belt 28. In this process, an L signal is outputted as a generation electric signal while the starter motor 23 drives the engine 3, however, an H signal is outputted when the engine 3 is started. Therefore, it is determined that the engine 3 is started if the H signals are continuously detected three times, for example, and the starter motor 23 is controlled so as to be stopped.