An ultrasonic transducer 1 includes two metal blocks 2, a plurality of piezoelectric elements 3 stacked between the metal blocks 2, a bonding material 4 bonding the metal blocks 2 and the piezoelectric elements 3, and the piezoelectric elements 3 to each other, and a heterogeneous material part 5 having a thermal expansion coefficient differed from a thermal expansion coefficient of the metal block 2 and provided in a notch part 2b formed at an end portion of the metal block 2 on a bonding plane side with respect to the piezoelectric element 3.
