A biophoton measuring instrument comprises a light illuminating section for illuminating a sample with a light having a predetermined wavelength and reactive with oxidized hemoglobins and reduced hemoglobins through an illuminating optical fiber, a light detecting section for detecting and amplifying the light passing through a detecting optical fiber and the sample, a signal processing section adapted for computing the hemoglobin temporal variation information on the oxidized hemoglobins, the reduced hemoglobins and the whole hemoglobins in the sample from the signal detected by the light detecting section and having noise detecting means for arithmetically processing the detected signal and judging/detecting whether the temporal variation information is the noise (low S/N noise) attributed to the presence of an obstacle to the pass of the light between the sample and the end face of the optical fiber or the noise (mirror noise ) attributed to the damage to the light illuminating section, and a display section for displaying the noise signal judged/detected by the signal processing section to enable identification of the type of the noise.
BIOPHOTON MEASURING INSTRUMENT