To quantitatively and accurately calculate a misaligned angle of a puncture needle relative to an ultrasound probe with ease.SOLUTION: An ultrasound diagnostic apparatus comprises: a transmission unit which has a plurality of transducers arrayed in a long axis direction in each region of a plurality of regions arranged in a short axis direction, and which transmits a drive signal of each region arranged in the short axis direction to an ultrasound probe 2 that is capable of transmitting and receiving ultrasound waves independently for each region； a reception unit which receives a reception signal of each region from the ultrasound probe 2； an image generation unit which generates ultrasound image data from the received reception signal of each region； an extraction unit which extracts an image of a puncture needle 3 from the generated ultrasound image data of each region； and a misaligned-angle calculation unit which calculates a misaligned angle θ of the puncture needle 3 relative to the ultrasound probe 2, using boundary position information in the extracted image of the puncture needle 3 for each region.SELECTED DRAWING: Figure 4【課題】超音波探触子に対する穿刺針のずれ角度を定量的に容易かつ精度よく算出することである。【解決手段】超音波診断装置は、短軸方向に複数の領域に配列され各領域で長軸方向に配列された複数の振動子を有し、短軸方向の複数の領域でそれぞれ独立して超音波の送受信が可能な超音波探触子２に、各領域の駆動信号を送信する送信部と、超音波探触子２から各領域の受信信号を受信する受信部と、受信された各領域の受信信号から超音波画像データを生成する画像生成部と、生成された各領域の超音波画像データから穿刺針３の画像を抽出する抽出部と、抽出された各領域の穿刺針３の画像の境界位置情報を用いて、超音波探触子２に対する穿刺針３のずれ角度θを算出するずれ角度算出部と、を備える。【選択図】図４
