To display the image of a reflection source with high accuracy in position by creating a hologram corresponding to an echo in a range of flaw detection, reproducing it by a predetermined method, displaying its image as a three-dimensional image, and reducing the effects of spread of ultrasonic waves.

An ultrasonic probe 101 is brought into contact with a body to be inspected 102 such as a steel plate as moving the ultrasonic probe 101 to repeat transmission and reception, and the obtained data is stored. By processing the data through the use of a predetermined threshold value, a diagram indicating an echo from a reflection source 103 is obtained. The diagram is rotated by an angle of rotation 115 corresponding to the angle of refraction of ultrasonic waves 115, etc., to obtain a hologram reproduction region 120. A hologram 121 is obtained by a process using a one-way transmission distance 119, and a reproduction image 123 corresponding to the refraction source 103 is obtained by processes such as high-speed Fourier transformation. By performing two-dimensional reproduction processes, etc., a three-dimensional image is created. The value of wave number used for hologram computations is selected so as to obtain optimal resolution.