An optical measuring instrument 1 is equipped with an optical system 20 to be used for measuring a characteristic of the aqueous humor in the anterior chamber 13 of an eyeball 10 of a measurement subject person and a holding unit 50 which holds the optical system 20 etc. The optical system 20 is equipped with a light emitting system 20A and a photodetecting system 20B. An optical path 28 is set so that light emitted from the light emitting system 20A passes through (traverses) the anterior chamber 13 and is detected by the photodetecting system 20B in a state that the eyeball 10 is turned outward.
