CLEANING DEVICE, MEASUREMENT METHOD, AND CALIBRATION METHOD

PROBLEM TO BE SOLVED: To provide a cleaning device capable of effectively and stably cleaning a substrate, and a calibration method of a dissolved gas concentration measurement instrument and a dissolved gas concentration measurement method, which are used for the cleaning device.SOLUTION: The calibration method of a measurement instrument which measures a concentration of gas dissolved in a liquid executes a step (S10) of varying the concentration of gas dissolved in a liquid to preliminarily determine the concentration of the gas, which gives a peak to the intensity of light emission due to ultrasonic irradiation on the liquid, as a reference concentration. Next, the calibration method executes a step (S20) of irradiating the liquid with an ultrasonic wave while varying the concentration of the gas in the liquid and, when the intensity of light emission shows a peak, measuring the concentration of nitrogen in a cleaning liquid by a measurement instrument being a calibration object, to determine a measurement value of the concentration of nitrogen. The calibration method executes a step (S30) of calibrating the measurement instrument as the calibration object on the basis of the measurement value and the reference concentration.