A magnetic field communication device of an online electric vehicle using electromagnetic induction of the present invention comprises: an electromagnetic induction device which is provided in the online electric vehicle, and performs electromagnetic induction by converting direct current power into alternating current power; and a resonant load device which is laid under the road on which feeding rails are equipped, and provides magnetic field communication by the energy that is electromagnetically induced from the electromagnetic induction device. According to the present invention, when the online electric vehicle passes through the feeding rails or stops, communication is enabled among the online electric vehicle, the feeding rails, and an inverter. Therefore, if a signal is transmitted to a secondary circuit through a switch, a sensor and the like in case of emergency which is sensible by the online electric vehicle, the inverter receives the signal and blocks the feeding rails.