According to the present invention, a displacement measurement unit measures, on the basis of a reception signal corresponding to a tracking wave reception beam obtained from a reception unit, the displacement of a tissue inside a subject after the generation of a shear wave. A fluctuation detection unit detects periodic displacement on the basis of the displacement measurement result obtained from the displacement measurement unit. A shear wave speed calculation unit calculates the propagation speed of a shear wave in the subject on the basis of the measurement result obtained from the displacement measurement unit and the detection result obtained from the fluctuation detection unit.
