A method for determining an appropriateness of a calculated pulse rate is provided. In a pulse rate monitor, a pulse rate calculation part calculates the pulse rate of the test subject based on the result detected by a pulse wave sensor. Then, a pulse rate difference calculation part calculates a difference (pulse rate difference) between a reference pulse rate and a calculated pulse rate, and a deviation degree is determined based on the pulse rate difference. Also, a SN ratio calculation part calculates a SN ratio of a pulse wave signal detected by the pulse wave sensor, and a reliability of the calculation result in the pulse rate calculation part is determined based on the SN ratio. Then, a pulse rate appropriateness judgment part determines an appropriateness of the calculated pulse rate based on the pulse rate difference (deviation degree) and the SN ratio (reliability).
