Disclosed herein is a circuit for preventing a malfunction of an arc fault detection device for determining whether an arc fault occurs through a low-current route or a high-current route, classified according to the magnitude of load current, using a source voltage applied to a conductor, which sets an operational prohibition range so as to prevent the malfunction of determining a pseudo-arc signal attributable to various combinations of loads to be an actual arc signal and interrupting a circuit, thus being capable of more precisely controlling the detection of the arc signal.