PURPOSE: To know the state immediately before the apnea state of a newborn during a sleeping time, by calculating not only waveform interval variation from electrocardiographic data but also the envelope data of a waveform from respiration data to calculate cross-correlation and evaluating the relation between the advance and delay of respiration and a heartbeat in a value high in correlation.

CONSTITUTION: The data from on examinee being a newborn 11 are detected by an electrocardiographic detection part 12 and a respiration detecting part 13. Next, said data are taken in a 20M hard disk being a recording apparatus 15 in a form of a random access file using an A/D converter 14 so as to be capable of performing analysis on a microcomputer 16. Electrocardiographic data is detected from a living body with respect to a heartbeat on the basis of the evaluation of respiration and heart electricity and, after the detection of the peak (R) value of an electrocardiographic waveform and the correction of base line are performed, an R-R interval variation time series is calculated. At the same time, with respect to respiration, respiration data is detected from a living body at first and a respiration waveform is detected to perform the Fourier transform of R-R interval time series variation. Next, a frequency spectrum is multiplied and the correlational operation of respiration and a heartbeat is performed by inverse Fourier transform. Then, the advance and delay of respiration and the heartbeat are evaluated from the correlation value.