Method and apparatus for performing ultrasonic flaw detection

According to a method of performing ultrasonic flaw detection, a pulse signal is output to an ultrasonic probe attached through an ultrasonic wave propagation medium to an object to be tested, a reflected wave of the ultrasonic wave incident on the object is received by the ultrasonic probe to obtain an echo signal. The carrier frequency of the pulse signal is set so that the peak frequency of the echo signal becomes a predetermined frequency, and then the cycle count of the pulse signal is set so that the frequency bandwidth of the echo signal becomes a predetermined bandwidth. A defect present in the object is detected in accordance with the echo signal output from the ultrasonic probe. According to an apparatus for performing ultrasonic flaw detection, an ultrasonic transmitter transmits a pulse signal having a designated carrier frequency and a designated cycle count to an ultrasonic probe. An ultrasonic receiver receives the echo signal output from the ultrasonic probe. The peak frequency and the frequency bandwidth of the echo signal received by the ultrasonic receiving unit are detected by a signal analysis unit. A transmission control unit designates the carrier frequency and the cycle count of the pulse signal output from the ultrasonic transmission unit so that the detected peak frequency and the detected frequency bandwidth become a flaw detection condition peak frequency and a flaw detection condition frequency bandwidth, respectively.