In order to measure a pulse rate and an oxygen saturation of a subject who is in an exercised state, each of two pulse wave signals obtained from the subject is separated into a signal component and a noise component. A frequency spectrum of the signal component and a frequency spectrum of the noise component are obtained. It is judged whether a body motion of the subject is occurred based on the frequency spectrum of the signal component and the frequency spectrum of the noise component. A pulsation frequency is determined based on the judgment as to the body motion. The pulse rate is calculated based on the pulsation frequency. The oxygen saturation is calculated based on a ratio of spectra of the two pulse wave signals corresponding to the pulsation frequency.
