A biological body state estimation device which acquires a biological signal from an upper body of the human being and estimates a state of a human being by using the biological signal, characterized in that the biological body state estimation device comprises: frequency calculating means for determining a time-series waveform of a frequency from a time-series waveform of a biological signal acquired by the biological signal measuring means; frequency slope time-series analysis calculating means for subjecting the time-series waveform of the frequency of the biological signal acquired by the frequency calculating means to movement calculation for determining a slope of the frequency at each predetermined time window set with a predetermined overlap time, and for outputting a time-series change in the slope of the frequency acquired at each time window as a frequency slope time-series waveform; characterised in that the biological body state estimation device further comprises spectrum time-series change calculating means for analyzing a frequency of the frequency slope time-series waveform acquired by the frequency slope time-series analysis calculating means, and for determining a time-series change in a power spectrum; distribution rate waveform calculating means for extracting frequency components corresponding to a preset functional adjustment signal, fatigue reception signal and activity adjustment signal from the time-series change in the power spectrum acquired by the spectrum time-series change calculating means, for calculating proportions of the three frequency components in time sequence when a sum of power spectrums of the three frequency components is set to 100, and for determining the proportions as distribution rate waveforms; and determining means for locating a waveform change pattern of the three frequency components in the distribution rate waveforms acquired by the distribution rate waveform calculating means, and for determining a state of a human being by comparing the located waveform change pattern with correlative data between a waveform change pattern and a state of a human being which the correlative data is stored in a storage unit in advance. frequency calculating means for determining a time-series waveform of a frequency from a time-series waveform of a biological signal acquired by the biological signal measuring means; frequency slope time-series analysis calculating means for subjecting the time-series waveform of the frequency of the biological signal acquired by the frequency calculating means to movement calculation for determining a slope of the frequency at each predetermined time window set with a predetermined overlap time, and for outputting a time-series change in the slope of the frequency acquired at each time window as a frequency slope time-series waveform; characterised in that the biological body state estimation device further comprises spectrum time-series change calculating means for analyzing a frequency of the frequency slope time-series waveform acquired by the frequency slope time-series analysis calculating means, and for determining a time-series change in a power spectrum; distribution rate waveform calculating means for extracting frequency components corresponding to a preset functional adjustment signal, fatigue reception signal and activity adjustment signal from the time-series change in the power spectrum acquired by the spectrum time-series change calculating means, for calculating proportions of the three frequency components in time sequence when a sum of power spectrums of the three frequency components is set to 100, and for determining the proportions as distribution rate waveforms; and determining means for locating a waveform change pattern of the three frequency components in the distribution rate waveforms acquired by the distribution rate waveform calculating means, and for determining a state of a human being by comparing the located waveform change pattern with correlative data between a waveform change pattern and a state of a human being which the correlative data is stored in a storage unit in advance.