<p>A calibration module (4) comprising: a calibration member (45) that is the target for irradiation of illumination light irradiated from the tip of a measurement probe (3); a fixed section (44) comprising an elastic body and having an insertion section (441) that is capable of having a tip section (33) of the measurement probe (3) inserted therein and has an inner diameter (D4) that is smaller than the outer diameter (D3) of the measurement probe (3); a first tube section (42) having the fixed section (44) provided therein and holding the calibration member (45) such that same is movable along the insertion direction of the measurement probe (3); and an impelling member (46) that impels the calibration member (45) towards the fixed section (44).</p>
