PROBLEM TO BE SOLVED: To provide an electromagnetic ultrasonic flaw detection method and an electromagnetic ultrasonic flaw detection apparatus for measuring defects with an improved S/N ratio and setting a high evaluation even if reflection waves by separate defects spread in the direction of a time axis in ultrasonic flaw detection using an electromagnetic ultrasonic sensor.;SOLUTION: By using the electromagnetic ultrasonic sensor 3 that has a permanent magnet 1 and a coil 2, and controls an incidence angle θ in ultrasonic waves by changing a frequency (f) in an AC current flowing to the coil 2, the incidence angle θ of ultrasonic waves is changed successively, direct arrival waves 8 propagated on the surface of piping 5 to be inspected, one-time bottom surface reflection arrival waves 9 reflected on the bottom surface once, and second-time bottom surface reflection arrival waves 10 reflected on the bottom surface twice are selected to detect reflection waves by the defects 6, thus acquiring the time-axis waveform data of respective reflection waves by transmitting and receiving ultrasonic waves and performing conversion processing to the waveform data in an axial distance axis.;COPYRIGHT: (C)2006,JPO&NCIPI
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