PROBLEM TO BE SOLVED: To allow driver drowsiness to be determined highly accurately in a drowsiness determination method, device, and program.SOLUTION: A drowsiness determination method for determining drowsiness of a subject on the basis of a drowsiness scale is constituted so that a computer executes the following steps of: obtaining heartbeat interval data by arranging an RRI (R-R Interval) in time series on the basis of a heartbeat waveform of the subject in a rest state with stable breathing measured by a sensor subjecting the heartbeat interval data to frequency-analysis to determine the frequency analysis result of heartbeat fluctuation that includes power spectral density (PSD) for a frequency at a certain time and total power (TP) of autonomous nerve setting the frequency analysis result as an initial state and determining a drowsiness scale in which the origin of a drowsiness position and the origin of an awakening position are set, on the basis of an estimated drowsiness position and an estimated awakening position contained in the initial state, and storing the determine scale in a storage medium.
