A residual anaerobic work capacity calculating method includes a step (S1) of obtaining a heart rate, and a step (S2, S3) of calculating a residual anaerobic work capacity based on the obtained heart rate and a relationship between the residual anaerobic work capacity and the heart rate. This method need only measure the heart rate when calculating the residual anaerobic work capacity, and obviates the need to measure power by using an expensive power meter.