A biological optical measurement instrument includes a single temperature sensor that detects a radiation temperature from a plurality of light emitting elements that emit light of a predetermined wavelength, and an absorption coefficient correcting unit that corrects an absorption coefficient value of a notable substance inside the object on the basis of the radiation temperature detected by the temperature sensor, referring to data indicating a correspondence relationship between a temperature obtained in advance for each emitted light of the plurality of light emitting elements and an absorption coefficient value that varies according to the temperature.
