PROBLEM TO BE SOLVED: To provide an ultrasonic vibrator which prevents breakage at the time of joining material having an anisotropic thermal expansion coefficient, reduces stress and has excellent vibration transmission efficiency at the occurrence of ultrasonic vibration, and an ultrasonic medical device.SOLUTION: An ultrasonic vibrator 1 comprises two metal blocks 2, a plurality of piezoelectric elements 3 laminated between the metal blocks 2, and joint material 4 joining the metal blocks 2 and the piezoelectric elements 3, and the piezoelectric elements 3 each other. The piezoelectric element 3 consists of anisotropic material in which a thermal expansion coefficient in an x direction is different from a thermal expansion coefficient in a y direction when one direction is defined as the x direction and the direction orthogonal to the x direction is defined as the y direction on a joint surface with the metal block 2. The metal block 2 is formed with a groove 21 defined in accordance with the difference in thermal expansion coefficient from the piezoelectric element 3 in the x direction or the y direction.COPYRIGHT: (C)2016,JPO&INPIT【課題】 異方性の熱膨張係数を有する材料を接合する際の破損を防ぎ、応力を低減し、超音波振動発生時の振動伝達効率が良好な超音波振動子及び超音波医療装置を提供する。【解決手段】 超音波振動子1は、2つの金属ブロック2と、金属ブロック2の間に積層される複数の圧電素子3と、金属ブロック2と圧電素子3及び圧電素子3同士を接合する接合材4と、を備え、圧電素子3は、金属ブロック2との接合面内において、一方向をx方向、当該x方向に直交するy方向に対して、x方向の熱膨張係数とy方向の熱膨張係数とが異なる異方性の材料からなり、金属ブロック2は、x方向又はy方向のうち、圧電素子3との熱膨張係数の差に応じて定められた溝21が形成されることを特徴とする。【選択図】図1
