An ultrasonic oscillator unit comprising: an ultrasonic oscillator array in which a plurality of ultrasonic oscillators having a rod shape are arranged in a circular-arc shape while aligning in a longitudinal direction of the rod shape; an electrode part that is provided in at least one end surface of the plurality of ultrasonic oscillators perpendicular to the longitudinal direction and has a plurality of electrodes electrically connected to the plurality of ultrasonic oscillators, respectively; a circular-arc backing material layer disposed on a rear surface of the ultrasonic oscillator array that becomes a center side of the circular-arc shape, wherein the backing material layer has an outer surface having a circular-arc cross-section on the rear surface of the ultrasonic oscillator array and has a recess on a side opposite to the outer surface ; three or more electrode wiring boards electrically connected to the plurality of electrodes of the electrode part ; and three or more connectors to which a plurality of cables are connected, respectively, wherein at least portions of the three or more connectors are disposed within the recess of the backing material layer ; wherein the three or more electrode wiring boards are respectively mounted to the three or more connectors and electrically connect the plurality of electrodes of the electrode part to the plurality of cables , and wherein the three or more connectors are arranged in a width direction of the backing material layer in the longitudinal direction on a rear surface side of the backing material layer opposite to the ultrasonic oscillator array . an ultrasonic oscillator array in which a plurality of ultrasonic oscillators having a rod shape are arranged in a circular-arc shape while aligning in a longitudinal direction of the rod shape; an electrode part that is provided in at least one end surface of the plurality of ultrasonic oscillators perpendicular to the longitudinal direction and has a plurality of electrodes electrically connected to the plurality of ultrasonic oscillators, respectively; a circular-arc backing material layer disposed on a rear surface of the ultrasonic oscillator array that becomes a center side of the circular-arc shape, wherein the backing material layer has an outer surface having a circular-arc cross-section on the rear surface of the ultrasonic oscillator array and has a recess on a side opposite to the outer surface ; three or more electrode wiring boards electrically connected to the plurality of electrodes of the electrode part ; and three or more connectors to which a plurality of cables are connected, respectively, wherein at least portions of the three or more connectors are disposed within the recess of the backing material layer ; wherein the three or more electrode wiring boards are respectively mounted to the three or more connectors and electrically connect the plurality of electrodes of the electrode part to the plurality of cables , and wherein the three or more connectors are arranged in a width direction of the backing material layer in the longitudinal direction on a rear surface side of the backing material layer opposite to the ultrasonic oscillator array . <EOS>