A diagnostic ultrasound apparatus is provided with: an ultrasound probe； a transceiver unit for transmitting and receiving an ultrasound beam from the ultrasound probe to a subject and processing reception signals output from the ultrasound probe to generate reception data； a complex data-generating unit for generating first complex data comprising amplitude information and phase information from quadrature detection of the reception data generated in the transceiver unit using a first center frequency and a first cutoff frequency and generating second complex data by quadrature detection of data that is the same as the reception data using a second center frequency that is lower than the first center frequency and a second cutoff frequency； a B-mode processing unit for generating a B-mode image using amplitude information for the first complex data and/or the second complex data； a phase difference-calculating section for calculating a first phase difference between frames using phase information for the first complex data and calculating a second phase difference between frames using phase information for the second complex data； a phase difference-correcting section for correcting the first phase difference using the second phase difference； and a displacement-calculating section for calculating, using the corrected first phase difference, the displacement of a tissue in a subject that is to be measured.La présente invention concerne un appareil de diagnostic ultrasonore qui comprend : une sonde ultrasonore ； une unité émettrice-réceptrice permettant d'émettre et de recevoir un faisceau ultrasonore, de la sonde ultrasonore jusqu'à un sujet, et de traiter des signaux de réception émis par la sonde ultrasonore pour générer des données de réception ； une unité de génération de données complexes permettant de générer des premières données complexes comprenant des informations d'amplitude et des informations de phase à partir d'une détection en quadrature des données
