Abstract: A bearing failure judging apparatus correctly judges the type of the cause of a failure of a bearing by synthetically judging many factors found in a vibrating waveform of a vibration produced when a failure takes place in the bearing i.e. various features of the time-waveform; a localization of the amplitudes of the time-waveform, the periods of pulsating waves, a degree of the acuteness of the waveform depicted by its envelope, the presence or absence of the proper peak value in the frequency spectra, and a change of the waveform after a given time.

Abstract: A system for detecting whether a machine is in the normal or abnormal state by comparing detected values of waveforms of signals such as vibration generated from the machine with a set value a plurality of times to indicate failure of the machine when the detected values reach the set value a predetermined number of times.