An object of the present invention is to reduce the amount of calculation and improve the uniformity of acoustic line signal quality when using the synthetic aperture method. An ultrasonic signal processing apparatus is configured to select a transmission transducer row from a plurality of transducers arranged in an ultrasound probe and to drive transmission ultrasound from the transmission transducer row. A transmitting unit that outputs a signal to the ultrasonic probe and repeats a transmission event while changing the position of the transmitting transducer row, and receives and receives a signal based on a reflected ultrasonic wave obtained according to the transmission event from the ultrasonic probe. A receiving unit that generates a signal sequence, an observation point setting unit that sets an observation point at each position in the subject corresponding to each of the transmission events, and a frame acoustic line signal based on the received signal sequence for each of the observation points And a frame generation unit that generates an image. The observation point setting unit determines that each observation point corresponds to one transmission event for observation points corresponding to an area closer to the ultrasound probe than the focus area. It is set to. [Selection diagram] FIG.【課題】合成開口法を用いる際に、演算量を低減し、かつ、音響線信号の品質の均一性を向上する。【解決手段】超音波信号処理装置であって、超音波プローブに列設された複数の振動子から送信振動子列を選択して前記送信振動子列から送信超音波が送信されるように駆動信号を超音波プローブに出力する送信イベントを送信振動子列の位置を変更しながら繰り返し行う送信部と、送信イベントに応じて得られた反射超音波に基づく信号を超音波プローブから受信して受信信号列を生成する受信部と、送信イベントのそれぞれに対応して被検体内の各位置に観測点を設定する観測点設定部と、観測点のそれぞれについて受信信号列に基づいてフレーム音響線信号を生成するフレーム生成部とを備え、観測点設定部は、フォーカス領域よりも超音波プローブに近い領域に対応する観測点について、各観測点が１つの送信イベントに対応するように設定する。【選択図】図５
