A calibration apparatus and a calibration method capable of executing a plurality of calibration items in one operation are provided. A reference reflection plate 43, which is arranged at a position away from a distal end portion of a measurement probe 3 by a predetermined distance L in a state in which the measurement probe 3 has been inserted in an insertion portion 41a, has a uniform reflectivity over a range of wavelength to be measured in an irradiation plane, and has stable reflection properties, is included, and a scattering mean free path of a material forming the reference reflection plate 43 is greater than a spatial coherence length Lsc determined using the predetermined distance L for the reference reflection plate 43.
