To accurately focus ultrasonic waves at a desired focal point by grasping the shape of a tissue boundary of an inspection target.SOLUTION: Ultrasonic waves are transmitted to an inspection target from a probe in which a plurality of transducers are arranged, and reception signals obtained by receiving ultrasonic waves returning from the inspection target after the transmission respectively by the transducers are used to detect a tissue boundary in the inspection target. At the detected tissue boundary, a path for the ultrasonic waves to be refracted is obtained, and a delay time of the ultrasonic waves to be transmitted for each transducer for focusing the ultrasonic waves at a predetermined focal point on the basis of the path is calculated for each transducer. Ultrasonic waves delayed by the delay time of each transducer are transmitted from each transducer to focus the ultrasonic wave.SELECTED DRAWING: Figure 1【課題】検査対象の組織境界の形状を把握し、所望の焦点に超音波を精度よく集束させる。【解決手段】複数の振動子が配列された探触子から検査対象に超音波を送信し、送信後に検査対象から戻る超音波を振動子がそれぞれ受信した受信信号を用いて、検査対象内の組織境界を検出する。検出した組織境界において、超音波が屈折する経路を求め、経路に基づいて所定の焦点に超音波を合焦させるための振動子ごとの送信する超音波の遅延時間を振動子ごとに算出する。振動子ごとの遅延時間により遅延させた超音波を各振動子から送信して焦点に超音波を集束させる。【選択図】図１
