There is a need to be able to perform optical calibration according to changes in measurement situations after the start of measurement.An LED 21 irradiates light to a subject. An optical detector 22 outputs an optical detection signal. A signal quality calculation portion 14 calculates signal quality of a pulsation signal generated based on the optical detection signal. A body motion level determination portion 15 determines whether the subject maintains a quiescent state based on acceleration detected by an acceleration sensor. A light intensity determination portion 16 determines luminescence quantity of the LED 21 based on the signal quality of the pulsation signal when the subject is determined to maintain a quiescent state.
