An ultrasound diagnostic device includes a propagation information estimator that evaluates reliability of wavefront arrival time data in the wavefront arrival time frame data and, for reliability nonconformance wavefront arrival time data in the wavefront arrival time frame data that does not satisfy a predefined condition, generates compensated wavefront arrival time data by interpolation based on wavefront arrival time data that does satisfy the predefined condition, replaces the reliability nonconformance wavefront arrival time data with the compensated wavefront arrival time data, and generates compensated wavefront arrival time frame data； and an elastic modulus calculator that calculates shear wave propagation speed and/or elastic modulus frame data in the region of interest, based on the compensated wavefront arrival time frame data.
