An object is to accurately grasp the position and the like of the transducer in an ultrasonic oscillator that retains the transducers in a deformable concave portion and moves the transducer in accordance with deformation of the concave portion. An ultrasonic oscillator retains transducers on a deformable concave portion, the transducers move in conformity with deforming of the concave portion, and the controller comprises receiver that receives sensing signals output from the sensing side transducers which sensed the ultrasonic waves oscillated from the oscillation side transducers, a distance calculation unit that calculates the distance between the oscillation side transducer and the sensing side transducer based on propagation time of the direct wave, an angle calculation unit that calculates a visual angle between a center axis of oscillation and the sensing side transducer viewed from the oscillation side transducer based on the sensing signal related to the direct wave, and a correction unit that corrects position information indicating a relative positional relationship between the plurality of transducers by using the distance and the visual angle.
