The present invention provides a power cutoff device automatically operated upon the occurrence of a spark on an electric wire. The power cutoff device of the present invention automatically cuts off power supply to an earth leakage breaker or an electronic switch according to a control signal transmitted by detecting an electromagnetic wave due to an electric spark generated on an electric wire by an abnormal state such as a connection failure of an electrical device, thus preventing a disaster such as an electrical fire caused by the electric spark (flame). According to the present invention, since the power cutoff device provides an intrinsic function of the earth leakage breaker that operates in a state of an overload or electric leakage and the earth leakage breaker is operated by detecting the electric spark generated on the electric wire, it is possible to effectively prevent a disaster such as an electrical fire caused by the electric spark.