A method for automatic detection of CHF and AF with 12-bit RR interval time series using an electrocardiogram by using normalized RMSSD, sample entropy, and Shannon entropy, includes: (a) testing the electrocardiogram according to time from a subject (b) calculating normalized RMSSD of data obtained at step (a) (c) calculating sample entropy value of the data obtained at step (a) (d) calculating Shannon entropy value for each of sections divided at step (a) and (e) comparing the normalized RMSSD, the sample entropy, and the Shannon entropy values calculated at steps (a),(b), and (c), and detecting CHF and AF.
