A load body state is judged from time series data of an emphasis displacement inclination obtained by collecting displacement signal data of the load body state using a displacement signal collection sensor, determining a rate of change for every arbitrary interval of an original waveform as an original waveform displacement inclination at an operating unit, and at the same time, determining time series data of an average displacement inclination for every prescribed time period range from a plurality of original waveform displacement inclinations, and by determining an emphasis displacement inclination through slide calculation of time series data of the average displacement inclination for every prescribed sampling time.