An ultrasonic transducer includes: a piezoelectric transducer (1) emitting ultrasonic waves and a backing layer (4) provided in contact with a back side of the piezoelectric transducer (1) and attenuating ultrasonic waves that are emitted toward the back side of the piezoelectric transducer (1) and have an opposite phase to the phase of ultrasonic waves emitted toward a front side of the piezoelectric transducer (1). The acoustic tubes (5) are disposed in the backing layer (4) such that a longitudinal direction of each acoustic tube (5) is in line with a traveling direction of the ultrasonic waves emitted by the piezoelectric transducer (1) toward the front and the back side. The acoustic tubes (5) have mutually different lengths on the basis of a principle of an acoustic wave synthesis, and attenuate in whole or in part the ultrasonic waves emitted by the piezoelectric transducer (1) toward the backing layer (4).
