An ultrasonic transducer includes a substrate, a supporting film, and a piezoelectric element. The substrate includes an opening. The supporting film is configured on the substrate to cover the opening. The piezoelectric element is configured at a part of the supporting film. The part overlaps with the opening in a planar view in a thickness direction of the substrate. A thickness of the part of at a center of gravity in the planar view is smaller than a thickness of an outer edge portion of the part. The outer edge portion is closer to the substrate than the center to the substrate.