PURPOSE: To quickly execute an RR interval spectral analysis so as to contribute the early detection of an autonomic nervous fault by executing quickly the designation of a spectral analysis object range.

CONSTITUTION: In a first step Q1, RR interval data are inputted and in a second step Q2, a range for executing a spectral analysis in the inputted RR interval data is designated by inputting a numerical value and in a third step Q3, the spectral analysis is executed within a designated range and in a fourth step Q4, the result of its analysis is outputted.