PROBLEM TO BE SOLVED: To provide an ultrasound diagnostic apparatus using a shear wave and a plane wave as a detection wave to evaluate the stiffness of tissue, which ultrasound diagnostic apparatus suppresses the degradation of precision of shear wave propagation analysis and at same time reduces the transmitting and receiving frequency of the detection wave.SOLUTION: An ultrasound diagnostic apparatus detects a shear wave propagation velocity through push pulse transmission, and includes: a push pulse transmitter for transmitting a push pulse； a detection wave transceiver for transmitting, following the push pulse, a plane wave as a detection wave to a region of interest in a subject multiple times and receiving reflected detection waves from the subject so as to generate a plurality of reception signals in a time-series manner； a displacement detector for detecting the displacement of tissue in the region of interest caused by a shear wave； and a shear wave analyzer for detecting a propagation velocity of the shear wave based on the displacement. The detection wave transceiver transmits a series of detection waves following the push pulse such that a transmission interval of consecutive two detection waves at least includes a first transmission interval and a second transmission interval which is longer than the first transmission interval.SELECTED DRAWING: Figure 4【課題】せん断波と検出波としての平面波を用いて組織の硬さを評価する超音波診断装置において、せん断波の伝播解析の精度低下を抑止しながら検出波の送受信頻度を低下させる。【解決手段】プッシュパルスを送信してせん断波の伝播速度を検出する超音波診断装置であって、プッシュパルスを送信するプッシュパルス送信部と、プッシュパルスに続き平面波を検出波として被検体内の着目領域へ複数回送信し、被検体からの反射検出波を受信して複数の受信信号を時系列に生成する検出波送受信部と、せん断波による着目領域内の組織の変位を検出する変位検出部と、変位に基づいてせん断波の伝播速度を検出するせん断波解析部とを備え、検出波送受信部は、プッシュパルスに続く一連の検出波の送信において、連続する２つの検出波の送信間隔が、第１の送信間隔と、前記第１の送信間隔より長い第２の送信間隔とを少なくとも含むように、検出波を送信する。【選択図】図４
