Patent ID: 8813570

Claim:
An ultrasonic measuring method, comprising: providing at least one set of ultrasonic sensors, each of which comprises a pair of first ultrasonic sensor and second ultrasonic sensor, and placing the first ultrasonic sensor on one side of a coated product formed by applying a coating material by coating to one surface or both surfaces of a substrate made of metal and wound in the form of a roll, as viewed in a thickness direction of the coated product, via an air layer, while placing the second ultrasonic sensor on the other side of the coated product, via an air layer; and measuring a thickness of the coating material by transmitting ultrasonic waves between the first ultrasonic sensor and the second ultrasonic sensor, wherein said at least one set of ultrasonic sensors comprises at least one actual-measurement ultrasonic sensor set that measures the thickness of the coating material, and a calibration ultrasonic sensor set comprising a pair of first calibration ultrasonic sensor and second calibration ultrasonic sensor, aside from the first ultrasonic sensor and the second ultrasonic sensor; and the calibration ultrasonic sensor set performs calibration, during measurement of the thickness of the coating material, and the actual-measurement ultrasonic sensor set calculates the thickness of the coating material, using a measurement condition value obtained by the calibration ultrasonic sensor set.