An ultrasonic oscillator for generating an ultrasonic signal by transmitting and receiving ultrasonic waves to a subject ( 11 ) , and automatically generates the pressurization displacement position by adding a pressing force to the subject pressing mechanism ( 12 ) , the ultrasonic signal the a specimen elasticity image generating displacement measurement circuit for measuring an image for displacement of the ( 33 ) , and elastic modulus calculating circuit for calculating the modulus of elasticity of the subject based on the image for displacement amount ( 34 ) , the ultrasonic signal on the basis of a subject pressing mechanism for controlling displacement measurement circuit for measuring the control displacement of the ( 31 ) based on a pressurizing mechanism control circuit for controlling the automatic pressing mechanism ( 12 ) based on the control for the amount of displacement ( 32 ) , and further comprising , pressurizing mechanism control circuit ( 32 ) calculates a period control displacement amount based on the spontaneous displacement of the object is equal to or greater than a predetermined threshold value , the timing automatically pressurizing mechanism in accordance with the calculated period ( ultrasonic observation system is controlled to cause a pressing force added to 12 ) ( 1 ) .被検体へ超音波を送受信して超音波信号を生成する超音波振動子(11)と、被検体に押圧力を加えて加圧変位を発生させる自動加圧機構(12)と、超音波信号に基づき被検体の画像用変位量を計測する弾性画像生成用変位計測回路(33)と、画像用変位量に基づき被検体の弾性率を演算する弾性率演算回路(34)と、超音波信号に基づき被検体の制御用変位量を計測する加圧機構制御用変位計測回路(31)と、制御用変位量に基づき自動加圧機構(12)を制御する加圧機構制御回路(32)と、を備え、加圧機構制御回路(32)は、被検体の自発変位に基づく制御用変位量が所定の閾値以上となる周期を算出し、算出した周期に応じたタイミングで自動加圧機構(12)に押圧力を加えさせるように制御する超音波観測システム(1)。
