The present invention is configured such that output results of frequency analysis of a frequency slope time-series waveform of a biological signal are compared with preset corresponding data of output results of brain waves of different biological states to the output results. Accordingly, time-series variation in a biological state identified by a brain wave state and brain waves can be estimated using a biological index other than brain waves, in particular, the frequency analysis results of the frequency slope time-series waveform of a biological signal reflecting autonomic nervous function. As a result, there is no need for an electroencephalograph to be used, and thus brain waves or a biological state corresponding to brain waves can be estimated swiftly and with ease.
BIOLOGICAL STATE ESTIMATION DEVICE, BIOLOGICAL STATE ESTIMATION METHOD, COMPUTER PROGRAM, AND RECORDING MEDIUM