Disclosed is a technique capable of reducing deterioration of measurement accuracy and reproducibility due to a long measurement time and acquiring an ultrasound image with high diagnostic performance in measurement of a shear wave velocity of radiation pressure elastography. In the radiation pressure elastography, information relating to a motion (fluctuation) in a measurement region is extracted while detecting a shear wave from echo signals due to irradiation of tracking pulses, and is provided to a user as reliability information indicating the reliability of a measurement result. Further, a factor of the fluctuation is specified from the extracted information, and is presented to the user. Furthermore, when arithmetically averaging plural times of measurement results, weighting is performed using the reliability information.
