An ultrasonic transducer according to the present invention includes: a piezoelectric transducer (1) which emits and receives ultrasonic waves and a backing layer (4d) which is provided in contact with the rear of the piezoelectric transducer (1) and which attenuates the ultrasonic waves emitted in a rear direction from the piezoelectric transducer (1). The backing layer (4d) includes a plurality of acoustic tubes (5c) formed in the rear direction from a plane of the backing layer (4d) that is in contact with the piezoelectric transducer (1). Each of the acoustic tubes (5c) has a different length based on a principle of superposition of acoustic waves. The acoustic tubes (5c) include an acoustic tube (5c) 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.
