PROBLEM TO BE SOLVED: To suppress of missing of an elastic image in a nonconforming region with low reliability in wavefront arrival time data measured in instrumentation of an ultrasound elastic modulus.SOLUTION: Provided is an ultrasound diagnostic apparatus, comprising: a propagation information estimation unit which estimates the reliability of wavefront arrival time data in wavefront arrival time frame data, interpolates reliability-nonconforming wavefront arrival time data in the wavefront arrival time frame data based on wavefront arrival time data that satisfies a predetermined condition to generate compensated wavefront arrival time data, and substitutes the reliability-nonconforming wavefront arrival time data with the compensated wavefront arrival time data to generate compensated wavefront arrival time frame data； and an elasticity modulus calculation unit which calculates a propagation speed or elastic modulus of a shear wave in a region of interest based on the compensated wavefront arrival time frame data.SELECTED DRAWING: Figure 2【課題】超音波弾性率計測において、測定した波面到達時間データの信頼度が低い不適合領域における弾性画像の画像抜けを抑制する。【解決手段】超音波診断装置は、波面到達時間フレームデータ中の波面到達時間データの信頼度を評価し、波面到達時間フレームデータ中の信頼度不適合波面到達時間データを、所定の条件を満たす波面到達時間データに基づき補間して補償波面到達時間データを生成し、信頼度不適合波面到達時間データを補償波面到達時間データに置き換えて補償波面到達時間フレームデータを生成する伝播情報推定部と、補償波面到達時間フレームデータに基づき、関心領域内のせん断波の伝播速度、又は、弾性率を算出する弾性率算出部とを備えた。【選択図】図２
