A rotating electrical machine abnormal state detection apparatus is provided. The apparatus includes: a current signal acquisition unit, coupled to a rotating electrical machine, for acquiring a set of real-time current waveforms from the rotating electrical machine; a state characteristic database, pre-storing a plurality of abnormal state characteristics which respectively correspond to a plurality of abnormal states; and an abnormal state detection unit, coupled to the current signal acquisition unit and the state characteristic database, for performing signal analysis on the set of real-time current waveforms to produce a current state characteristic, and comparing the current state characteristic with the abnormal state characteristics pre-stored in the state characteristic database to determine the abnormal state of the rotating electrical machine.