An ultrasonic transducer element, comprising: a substrate; a lower electrode which is formed on a first principal surface of the substrate; a first insulating film which is formed on the lower electrode; a first cavity portion which is formed on the first insulating film; a second insulating film which is formed to surround the first cavity portion; an upper electrode which is formed on the second insulating film and disposed at a position overlapping with the first cavity portion when viewed in a top view from an upper surface of the substrate; a third insulating film which is formed on the upper electrode; a second cavity portion or a material layer having an elastic modulus lower than the third insulating film, wherein the second cavity portion or the material layer is formed on the third insulating film; a fourth insulating film which is formed to surround the second cavity portion or the material layer; wherein the ultrasonic transducer element further comprises, when viewed in the top view: a fixing portion which is formed by the second, third, and fourth insulating films surrounding an outer periphery of the first cavity portion; a movable portion which is a region inside the second cavity portion or the material layer in a membrane, the membrane being formed by the second, third, and fourth insulating films and the upper electrode formed on the first cavity portion; and a first connection portion and a second connection portion which is stacked with a gap from the first connection portion, the connection portions (3031, 3032) being formed by the second, third, and fourth insulating films connecting the movable portion and the fixing portion, characterised in that the second cavity portion or the material layer having a low elastic modulus compared to both the first and second connection portions (3031, 3032) is disposed such that an inner periphery thereof is disposed at a position overlapping with the first cavity portion compared to the first cavity portion, and part or all of an outer periphery thereof is disposed in a region outside a contour of a profile of the first cavity portion when viewed in the top view. a substrate; a lower electrode which is formed on a first principal surface of the substrate; a first insulating film which is formed on the lower electrode; a first cavity portion which is formed on the first insulating film; a second insulating film which is formed to surround the first cavity portion; an upper electrode which is formed on the second insulating film and disposed at a position overlapping with the first cavity portion when viewed in a top view from an upper surface of the substrate; a third insulating film which is formed on the upper electrode; a second cavity portion or a material layer having an elastic modulus lower than the third insulating film, wherein the second cavity portion or the material layer is formed on the third insulating film; a fourth insulating film which is formed to surround the second cavity portion or the material layer; wherein the ultrasonic transducer element further comprises, when viewed in the top view: a fixing portion which is formed by the second, third, and fourth insulating films surrounding an outer periphery of the first cavity portion; a movable portion which is a region inside the second cavity portion or the material layer in a membrane, the membrane being formed by the second, third, and fourth insulating films and the upper electrode formed on the first cavity portion; and a first connection portion and a second connection portion which is stacked with a gap from the first connection portion, the connection portions (3031, 3032) being formed by the second, third, and fourth insulating films connecting the movable portion and the fixing portion, a fixing portion which is formed by the second, third, and fourth insulating films surrounding an outer periphery of the first cavity portion; a movable portion which is a region inside the second cavity portion or the material layer in a membrane, the membrane being formed by the second, third, and fourth insulating films and the upper electrode formed on the first cavity portion; and a first connection portion and a second connection portion which is stacked with a gap from the first connection portion, the connection portions (3031, 3032) being formed by the second, third, and fourth insulating films connecting the movable portion and the fixing portion, characterised in that the second cavity portion or the material layer having a low elastic modulus compared to both the first and second connection portions (3031, 3032) is disposed such that an inner periphery thereof is disposed at a position overlapping with the first cavity portion compared to the first cavity portion, and part or all of an outer periphery thereof is disposed in a region outside a contour of a profile of the first cavity portion when viewed in the top view.