PROBLEM TO BE SOLVED: To provide an ultrasonic device, ultrasonic probe, and ultrasonic apparatus, having high transmission and reception sensitivity.SOLUTION: The ultrasonic device includes: a substrate having an opening and a partition wall surrounding the opening； a vibrating part closing one end side of the opening； and a piezoelectric element provided in the vibrating part. W/H is 0.66 to 0.92, where W is an opening width dimension of the opening and H is a thickness dimension of the substrate.SELECTED DRAWING: Figure 4【課題】高い送受信感度の超音波デバイス、超音波プローブ、及び超音波装置を提供する。【解決手段】超音波デバイスは、開口部及び前記開口部を囲う隔壁を有する基板と、前記開口部の一端側を閉塞する振動部と、前記振動部に設けられる圧電素子と、を備え、前記開口部の開口幅寸法をＷ、前記基板の厚み寸法をＨとした際に、Ｗ／Ｈが０．６６～０．９２である。【選択図】図４
