An ultrasonic element includes at least one cMUT provided to a substrate, wherein the cMUT includes a first electrode provided to the substrate, a frame member having a cavity, a second electrode disposed to face the first electrode with the cavity interposed between the second electrode and the first electrode, and a protective layer covering the second electrode, a length of the cavity in an X axis direction being longer than a width of the cavity in a Y axis direction, the protective layer having a convex region extending in the X axis direction, a width of the convex region in the Y axis direction varying.