Abstract: The present embodiment provides a partial discharge measurement apparatus configured to detect partial discharge generated in a rotating electrical machine supplying or receiving power via an insulated conductor, where the apparatus comprises a calibration signal generator, a sensor, a compensation processor, and a signal processor. The calibration signal generator is configured to supply a calibration signal to a surface of an insulating layer of the insulated conductor. The sensor is configured to measure a physical quantity regarding the partial discharge. The compensation processor is configured to use an output signal of the sensor when the calibration signal has been supplied to generate a compensation coefficient. The signal processor is configured to process the output signal of the sensor based on the compensation coefficient.