Patent ID: 8091426

Claim:
An ultrasonic wave measuring method of irradiating with an ultrasonic wave an object to be detected having a plurality of interfaces, detecting a waveform signal generated from the object, and observing a joint state of a boundary face of the object, the ultrasonic wave measuring method comprising: saving, for every observation spot of a reference object which cross-sectional structure, material, and thickness are the same as the object in a certain specific region within an XY plane orthogonal to a direction of irradiating with the ultrasonic wave, an entire waveform signal of the reference object or a waveform signal observed from near an interface part of the reference object as a reference signal in a reference signal storage section; acquiring in a calculating unit an ultrasonic wave waveform signal acquired at an observation spot of the object corresponding to the observation spot of the reference object and near the interface part to be observed in which a generating time region is limited from a thickness known in advance and a sonic speed of the ultrasonic wave; and comparing and calculating the ultrasonic wave waveform signal acquired from the object and the reference signal to obtain a relative value, and observing the joint state of the boundary face in the calculating unit, wherein in the observing of the joint state of the boundary face, the object having the plurality of interfaces is irradiated with the ultrasonic wave, the comparing and calculating is performed in the calculating unit between the waveform signal observed from the object and the reference signal, a time phase difference generated for every observed waveform signal is corrected in the calculating unit by having a point where the two waveform signals best match as a reference point, and thereafter quality determination is performed in a determining section by comparing waveform components within a predetermined time region in the XY plane specified in advance.