PROBLEM TO BE SOLVED: To display a region where a received signal contributes to a reconstructed image when the received signal includes data whose arrival time is difficult to measure. SOLUTION: An ultrasonic wave is transmitted a plurality of times while changing a transmission angle with respect to a subject, and an ultrasonic wave transmitted through the subject is received by an ultrasonic element array for each transmission. An ultrasonic wave is transmitted/received by the ultrasonic element array without arranging the subject and compared with the received signals respectively obtained by the ultrasonic elements to obtain a value indicating the reliability of the received signal for each ultrasonic element. A reliability map indicating the distribution of reliability in the cross section of the subject is generated by performing image reconstruction based on the value indicating the reliability of the reception signal of each ultrasonic element calculated for each reception by the reliability calculation unit. To do. [Selection diagram] Figure 1【課題】受信信号に到達時間の計測が困難なデータが含まれる場合、その受信信号が、再構成画像に寄与している領域を表示する。【解決手段】被写体に対して送信角度を変えながら超音波を複数回送信して前記送信ごとに被写体を透過した超音波を超音波素子列で受信した受信信号を得る。被写体を配置せずに超音波素子列によって超音波を送受信して超音波素子によりそれぞれ得た受信信号と比較することにより、その受信信号の信頼度を示す値を超音波素子ごとに求める。信頼度算出部が算出した受信ごとの前記各超音波素子の受信信号の信頼度を示す値に基づいて画像再構成をすることにより、被写体の断面における信頼度の分布を示す信頼度マップを生成する。【選択図】図１
