PROBLEM TO BE SOLVED: To provide an ultrasonic measuring apparatus which does not need to install a position of a light detecting unit with respect to a vibrating film with high positional accuracy in a plan view of a substrate.SOLUTION: An ultrasonic transducer device 1 includes: a substrate 2 having an opening portion 3； a vibration film 5 installed on the substrate 2； a piezoelectric element 9 being installed on the vibration film 5 and vibrating the vibration film 5； and a light detection unit 14 for detecting vibration of the vibration film 5 by using reflected light 15b. The light detection unit 14 is positioned at a side opposite to the substrate 2 with respect to the vibration film 5.SELECTED DRAWING: Figure 1【課題】基板の平面視において振動膜に対する光検出部の位置を位置精度良く設置しなくても良い超音波測定装置を提供する。【解決手段】超音波トランスデューサーデバイス１は開口部３を有する基板２と、基板２上に設置された振動膜５と、振動膜５上に設置され振動膜５を振動させる圧電素子９と、反射光１５ｂを用いて振動膜５の振動を検出する光検出部１４と、を備え、光検出部１４は、振動膜５に対して基板２の反対側に位置する。【選択図】図１
