This standard specifies the measurement principles, measurement conditions, measurement methods, measurement abnormal phenomena and their processing, measurement result evaluation and measurement report for ultrasonic flaw detection signal amplitude error. This standard is applicable to the measurement of the amplitude error of the flaw detection signal using a general-purpose A-scan pulse reflection ultrasonic flaw detector (hereinafter referred to as the ultrasonic flaw detector), and can also be used as a reference when using other types of ultrasonic flaw detectors for measurement.