To provide an apparatus and a program wherein the existence of an abnormality is detected with high accuracy regarding an abnormality monitoring apparatus which monitors the existence of the abnormality in a rotary machine continued to be turned at a slow speed.

An abnormality monitoring apparatus mainframe 500 is supplied will, a vibration waveform signal and an acoustic waveform signal from a vibration sensor 210A and a sonic sensor 210B, and control state information which expresses the present speed of rotation and the present rotational position (phase) of the rotary machine 300 from a machine controller 400. When the signals and the information are supplied, and inverted filter is found from each phase range when the rotary machine 300 is in a normal state, each phase range which is used to find the inverted filter and waveform data regarding the same phase range are fetched when the abnormality is monitored, the inverted filter in the same phase range is made to act on the waveform data so as to find a residual signal, and the existence of the abnormality is judged according to the power lever of the residual signal.