An ultrasound processing device including an interleaver that obtains a combined wavefront frame sequence by interleaving a plurality of wavefront frame sequences； and a calculator that calculates shear wave speed and elastic modulus in a subject, by performing calculations using change amounts of propagation positions of a shear wave indicated by the combined wavefront frame sequence. The interleaving by the interleaver comprises frame interleaving and/or element array direction interleaving.
