1. An abnormality factor identification apparatus for identifying a factor in an abnormality occurring in a machine, the apparatus comprising:a processor configured to
obtain sensor signals associated with a physical state of the machine,
determine operating states of the machine based on information obtained from the machine,
calculate abnormality levels of the sensor signals for each determined operating state of the machine, and
determine a factor in an abnormality in the machine from historical data being a series of the abnormality levels for said each determined operating state.