The weight value used for the phasing process of the received signal of the ultrasonic imaging apparatus is obtained accurately with a small amount of computation, although it is an adaptive signal processing technique. The ultrasonic signals from the subject are received by the plurality of elements 401, and the similarity between the received signals x (n) is obtained by the similarity calculation unit 404. Using the similarity C (n) between the received signals obtained by the similarity calculation unit 404, the adaptive weight calculation unit 407 obtains an adaptive weight w (n) corresponding to the similarity. The phasing calculation unit 408 generates a phasing output using the adaptive weight w (n) and the received signal x (n). The image processing unit 108 creates image data using the phasing output. For example, the similarity calculation unit 404 calculates the similarity in the time direction.超音波撮像装置の受信信号の整相処理に用いる重み値を、適応信号処理の手法でありながら、少ない演算量で精度よく求める。被検体からの超音波信号を複数の素子４０１で受信し、受信信号x(n)間の類似度を類似度演算部４０４により求める。類似度演算部４０４の求めた受信信号間の類似度C(n)を用いて、類似度に対応した適応重みw(n)を適応重み演算部４０７により求める。適応重みw(n)と受信信号x(n)とを用いて整相出力を整相演算部４０８により生成する。整相出力を用いて画像データを画像処理部１０８が作成する。例えば、類似度演算部４０４は、時間方向について類似度の演算を行う。
