A brain wave analysis device 30 includes a computation section 301 configured to compute a first ratio and a second ratio from a spectrum obtained by performing frequency analysis on time-series data of brain waves measured at a predetermined location of a head of a subject. The first ratio is either a ratio, with respect to a feature value that is a strength of one wave in a first frequency band generated in a stress-induced state, of a feature value that is a strength of another wave in the first frequency band present in a frequency band higher than the one wave, or a ratio of a feature value that is a strength of a wave in the first frequency band with respect to a feature value that is a strength of a wave in a second frequency band generated in an awake state. The second ratio is a ratio of a feature value that is a strength of a wave in a third frequency band generated in a sleeping state with respect to a feature value that is a strength of a wave in the second frequency band generated in an awake state. The brain wave analysis device 30 also includes an inference section 302 configured to infer a state of the subject based on the first ratio, a first reference value set using the first ratio, the second ratio, and a second reference value set using the second ratio.
ELECTROENCEPHALOGRAM ANALYSIS APPARATUS, ELECTROENCEPHALOGRAM ANALYSIS SYSTEM, AND ELECTROENCEPHALOGRAM ANALYSIS PROGRAM