Vibration wave radiating device

A vibration wave radiating device comprising:

• a vibrator to generate vibration;
• a vibrating body connected to the vibrator and including a front surface and a back surface closer to the vibrator and facing away from the front surface;
• and
• a reflecting plane portion facing the back surface of the vibrating body with a space therebetween;
• wherein
• the vibrating body includes a connection portion connected to the vibrator and a vibrating portion extending away from the reflecting plane portion and extending from an end portion of the connection portion opposite to the vibrator, the vibrating portion including the back surface facing the reflecting plane portion;
• the vibrating portion has a tubular shape linearly increasing in diameter from the connection portion in a longitudinal section;
• a peripheral edge of the reflecting plane portion is coaxial with a central axis of the vibrating portion and located outside the vibrating portion as viewed in a direction orthogonal to the reflecting plane portion;
• and
• when a distance between the connection portion and the reflecting plane portion in the direction orthogonal to the reflecting plane portion is TD, an angle defined by a virtual line parallel to the reflecting plane portion and the back surface of the vibrating portion in the longitudinal section is θ, a shortest distance between a peripheral edge of the back surface at an end of the vibrating portion opposite to the connection portion and the peripheral edge of the reflecting plane portion is L, and a wavelength of a vibration wave emitted from the vibrating portion is λ, a relationship indicated by 0.78λ≤L≤1.19λ or 1.5λ≤L≤2.14λ is satisfied when TD=0 and 35°≤θ≤55°.