In the figure, a circulatory-organ-relating-information obtaining means 70 iteratively obtains, as a sort of information relating to circulatory organ of a living subject, an interval-fluctuation-magnitude ratio PL/PH, that is, a ratio of (a) a low-frequency fluctuation magnitude PL of the heart rate values HR determined based the ECG signal SM2 supplied from the ECG device 34, to (b) a high-frequ