In order to develop the nondestructive testing technology for the cracks at the tube expansion region in steam generator ultrasonic technique using leaky surface wave was applied for the detection of simulated crack-like defects of the 304 stainless steel plate. The ultrasonic technique shows higher detectability for the simulated cracks than conventional eddy current technique (MRPC, Motorized Rotating Pancake Coil). The ultrasonic technique could reduce some error encountered in the measurement of crack length. However, since the ultrasonic technique is not a well-established method for the crack in steam generator tubings at present, it could be used as a supplementary method for improving reliability on the detection of crack-like defects and accurate measurement of the crack length, in addition to the basic eddy current technique (MRPC). (Author).