An ultrasonic transducer which can attenuate ultrasonic waves emitted toward the rear without increasing a thickness of a backing layer includes: a piezoelectric transducer which emits and receives ultrasonic waves and the backing layer which is provided in contact with the rear of the piezoelectric transducer and which attenuates the ultrasonic waves emitted in a rear direction from the piezoelectric transducer. The backing layer includes a plurality of acoustic tubes formed in the rear direction from a plane of the backing layer that is in contact with the piezoelectric transducer. Each of the acoustic tubes has a different length based on a principle of superposition of acoustic waves. The acoustic tubes include an acoustic tube which has (i) a portion of the length formed in a direction perpendicular to the rear direction and (ii) the remaining portion of the length formed in a direction parallel to the rear direction.
