Provided is a technique for more accurately ascertaining a person's status. In particular, the present invention makes it possible to accurately ascertain the detection of alcohol or the like. A fluctuation waveform of an ultra-low-frequency band is found from a biosignal collected from a biosignal measuring means, the fluctuation waveform is plotted as coordinate points on a four-quadrant coordinate system on the basis of a predetermined standard, and biological status is estimated on the basis of temporal change in the coordinate points. According to the method of the present invention for plotting a fluctuation waveform as coordinate points on a four-quadrant coordinate system on the basis of the predetermined standard, change in the fluctuation waveform of the ultra-low-frequency band can be expanded or highlighted and thus perceived, and therefore the present invention is adapted for more accurately perceiving change in a person's status.
