PROBLEM TO BE SOLVED: To provide an electrostatic capacitance type ultrasonic transducer which is small-sized and is capable of transmitting/receiving ultrasonic waves at frequencies of wide bands without reducing a transmission strength and a reception strength of ultrasonic waves, and to provide an ultrasonic diagnostic device and ultrasonic microscope.SOLUTION: In an ultrasonic transducer comprising a first electrode, a vibrating film disposed on the first electrode while being separated by a cavity hole portion and a second electrode supported on the vibrating film, the hole portion is configured by providing a plurality of void parts having different cross-sectional areas when viewed from a side of the second electrode successively in a direction from the first electrode to the second electrode.COPYRIGHT: (C)2009,JPO&INPIT【課題】小型であり、かつ超音波の送信強度及び受信感度を低下させずに広帯域の周波数で超音波を送受信することが可能な静電容量型の超音波トランスデューサ、超音波診断装置及び超音波顕微鏡を提供する。【解決手段】第1の電極と、該第1の電極上に空洞の穴部を隔てて配設された振動膜と、該振動膜に支持された第2の電極と、を具備した超音波トランスデューサにおいて、前記穴部を、前記第2の電極側から見た場合に異なる断面積を有する複数の空隙部を前記第1の電極から前記第2の電極へ向かう方向に連設して構成する。【選択図】図5
