PROBLEM TO BE SOLVED: To accurately measure at least blood oxygen concentration while suppressing noise.SOLUTION: A wrist fitting type pulse oximeter includes: a light emitting part having a first light emitting element for emitting infrared light of a first wavelength, and a second light emitting element for emitting infrared light of a second wavelength； a light receiving part for detecting the infrared light that is emitted from the light emitting part and passes through a wrist； and a calculation part for calculating a pulse and blood oxygen concentration from a light intensity signal acquired by the light receiving part. The first wavelength and the second wavelength are set so that an absorption coefficient of deoxygenated hemoglobin and oxygenated hemoglobin in the first wavelength, and an absorption coefficient of deoxygenated hemoglobin and oxygenated hemoglobin in the second wavelength are virtually the same.
