Patent ID: 8393218

Claim:
An ultrasonic testing method, comprising: a disposing step of disposing an ultrasonic probe including n (n≧2) number of transducers arranged along a predetermined direction so as to face a test object; a testing step of testing the test object by selecting m (n>m≧1) number of transducers from among the n number of transducers, transmitting ultrasonic waves from the selected m number of transducers toward the test object and receiving the ultrasonic waves therefrom; and a scanning step of switching m number of transducers to be selected successively, the method repeating the testing step and the scanning step alternately, thereby ultrasonic testing the test object, wherein, in the scanning step, if an angle that the arrangement direction of the n number of transducers makes with the surface of the test object which ultrasonic waves enter is θ(°), and the effective beam width of each selected m number of transducers with respect to a target flaw is W 1 (mm), m number of transducers to be selected are switched successively by a switching pitch length P (mm) satisfying the following formula (1): P≦W 1·cos θ (1) and, in the testing step, the test object is tested with testing sensitivity adjusted beforehand for each selected m number of transducers so that the highest echo intensities from target flaws received by each selected m number of transducers are approximately equivalent.