An atrial fibrillation detecting device includes a processor and a memory that stores a computer-readable command. When the computer-readable command is executed by the processor, the atrial fibrillation detecting device is configured to acquire pulse data representing a plurality of pulses, calculate a pulse rate based on the pulse data, calculate respective pulse amplitude indices of the plurality of pluses based on the pulse data, calculate an amplitude dispersion of the pulse amplitude indices based on the calculated pulse amplitude indices, calculate respective pulse interval indices of the plurality of pluses based on the pulse data, calculate an interval dispersion of the pulse interval indices based on the calculated pulse interval indices, and determine whether the pulse data is atrial fibrillation, based on the calculated pulse rate, the calculated amplitude dispersion, and the calculated interval dispersion.