An ultrasonic image processing method comprising: an image data production step of storing a result of detection, which is performed by a detection unit in order to detect an ultrasonic signal of a subject to which ultrasonic waves are irradiated by an irradiation unit, and producing at least two frame image data items, detection timings of which are different from each other, from the stored result of detection; a motion-vector distribution image production step of producing a motion-vector distribution image using a plurality of frames out of the image data items through predetermined motion-vector analysis processing; and a conversion step of converting the motion-vector distribution image into a scalar-distribution image according to a selected method on the basis of ROIs, that is, a plurality of set regions of interest, characterised in that: the conversion step includes a first processing step of setting a small region ROI to be noted within the motion vector distribution, permuting beam-direction components and azimuthal-direction components within the ROI with real-number components and imaginary-number components respectively, and thus converting the motion vector distribution within the ROI into a complex matrix, a second processing step of performing eigenvalue expansion processing on the complex matrix so as to obtain an eigenvalue matrix, and a third processing step of determining one scalar value by obtaining a maximum value of absolute values of eigenvalues (λ k) out of the eigenvalue matrix or obtaining a sum total of the absolute values of the eigenvalues (λ k); and the first to third processing steps are implemented on a plurality of ROIs within the motion vector distribution in order to produce a scalar-distribution image. an image data production step of storing a result of detection, which is performed by a detection unit in order to detect an ultrasonic signal of a subject to which ultrasonic waves are irradiated by an irradiation unit, and producing at least two frame image data items, detection timings of which are different from each other, from the stored result of detection; a motion-vector distribution image production step of producing a motion-vector distribution image using a plurality of frames out of the image data items through predetermined motion-vector analysis processing; and a conversion step of converting the motion-vector distribution image into a scalar-distribution image according to a selected method on the basis of ROIs, that is, a plurality of set regions of interest, characterised in that: the conversion step includes a first processing step of setting a small region ROI to be noted within the motion vector distribution, permuting beam-direction components and azimuthal-direction components within the ROI with real-number components and imaginary-number components respectively, and thus converting the motion vector distribution within the ROI into a complex matrix, a second processing step of performing eigenvalue expansion processing on the complex matrix so as to obtain an eigenvalue matrix, and a third processing step of determining one scalar value by obtaining a maximum value of absolute values of eigenvalues (λ k) out of the eigenvalue matrix or obtaining a sum total of the absolute values of the eigenvalues (λ k); and the first to third processing steps are implemented on a plurality of ROIs within the motion vector distribution in order to produce a scalar-distribution image. the conversion step includes a first processing step of setting a small region ROI to be noted within the motion vector distribution, permuting beam-direction components and azimuthal-direction components within the ROI with real-number components and imaginary-number components respectively, and thus converting the motion vector distribution within the ROI into a complex matrix, a second processing step of performing eigenvalue expansion processing on the complex matrix so as to obtain an eigenvalue matrix, and a third processing step of determining one scalar value by obtaining a maximum value of absolute values of eigenvalues (λ k) out of the eigenvalue matrix or obtaining a sum total of the absolute values of the eigenvalues (λ k); and the first to third processing steps are implemented on a plurality of ROIs within the motion vector distribution in order to produce a scalar-distribution image.