PURPOSE: To obtain an inexpensive partial discharge detecting device which can reduce the number of insulator fitting sections for detecting the partial discharge of electric equipment and, at the same time, can constitute a signal transmission system of one sequence of signal lines.

CONSTITUTION: This partial discharge detecting device is constituted in such a way that detectors 34 which detect partial discharge are respectively provided to insulator fitting sections and no-insulator fitting sections and output signals of the detectors 34 are connected in series by means of couplers 5 so that the output signals can be transmitted to a waveform shaper 6 through one sequence of signal lines and can be discriminated by means of the output pattern discriminator 7 of the shaper 6. Therefore, the number of insulator fitting sections can be reduced and, even when part of a high-voltage conductor in an abnormal position orientation section is disconnected, the abnormal position can be oriented. In addition, the abnormal position can be oriented by means of the one signal transmission line sequence and the input of one channel only.