The present device is equipped with a measurement site holder 3 that is constructed using a negative impression of the measurement site 10. As a result, variation in the measured values caused by the non-uniform distribution of components in the measurement site 10 is reduced, so that variation in the measured values caused by variations in the light path length accompanying variations in the shape of the measurement site 10, and by variations in blood flow or the like that accompany differences in the contact pressure, can be reduced. Since living-body information and measurement parameters for the patient are recorded on a recording medium 11 mounted on a measurement site holder 3 for the exclusive use of the individual patient, the erroneous acquisition of living-body information for individual patients can be prevented, and reproducible measurements can be performed.