PROBLEM TO BE SOLVED: To provide a heart rate detection method that accurately detects a heart rate and the time from data on a low sampling frequency of an electrocardiographic waveform.SOLUTION: A heart rate detection method includes: an R wave detection step of comparing a first threshold value Tfor identifying the sampling data on an electrocardiographic waveform and R wave, and detecting the sampling data becoming the representative point of the R wave (S6 to S10) an S wave detection step of comparing a second threshold value T(T>T) for identifying the sampling data on the electrocardiographic waveform and S wave, and detecting the sampling data becoming the representative point of the S wave (S1 to S5) and a heart rate time calculation step of detecting the sampling data on two points astride a third threshold value T(T>T>T) between the representative point of the R wave and the representative point of the S wave existing after this point, and calculating the time when a straight line of connecting the sampling data on these two points intersects with the third threshold value Tas the heart rate time (S11 to S14).
