A modulation frequency control unit (36) controls a displacement-use transmission unit (34) such that displacement-use ultrasonic beam (EB) is subjected to modulation processing using a relatively high modulation frequency and a relatively low modulation frequency. A displacement measurement unit (24) measures the displacement of a tissue in a treatment area (P) at each of the modulation frequencies, and a coagulation measurement unit (25) measures local coagulation in the treatment area (P) on the basis of the measurement result of the displacement at the relatively high modulation frequency, and measures wide-area coagulation in the treatment area (P) on the basis of the measurement result of the displacement at the relatively low modulation frequency. Consequently, for example, the presence or absence of local coagulation immediately after coagulation has occurred, and the like, can be measured with high accuracy, and further, for example, the size of wide-area coagulation after coagulation has progressed, and the like, can be measured with high accuracy.【課題】超音波を利用した組織の凝固の測定において測定精度を高める。【解決手段】変調周波数制御部36は、比較的高い変調周波数と比較的低い変調周波数を用いて変位用超音波ビームEBを変調処理するように変位用送信部34を制御する。変位測定部24は、各変調周波数ごとに治療部位Pにおける組織の変位を測定し、凝固測定部25は、比較的高い変調周波数による変位の測定結果に基づいて、治療部位Pにおける局所的な凝固を測定し、比較的低い変調周波数による変位の測定結果に基づいて、治療部位Pにおける広域的な凝固を測定する。これにより、例えば発生直後の局所的な凝固の有無などを高精度に測定でき、さらに、例えば進行後の広域的な凝固の大きさなどを高精度に測定できる。【選択図】図1
