An array of a plurality of ultrasonic transducers having a piezoelectric layer 2 and a couple of electrodes 7-1 and 7-2 sandwiching the piezoelectric layer therebetween is provided. The piezoelectric layer 2 has a first piezoelectric layer 2-1 provided on the ultrasonic-wave emission side, a second piezoelectric layer 2-2 provided on the other side of the first piezoelectric layer 2-1, and a common electrode 8 provided therebetween. Each of the ultrasonic transducers has a low-frequency response distribution that is uniform in the minor-axis direction perpendicular to a direction in which the ultrasonic transducers are arranged and a high high-frequency response distribution at a center part in the minor-axis direction. The characteristics of the minor-axis-direction frequency and sound pressure of the first piezoelectric layer are complemented by those of the second piezoelectric layer, whereby a uniform frequency characteristic for a minor-axis-direction low frequency is obtained.
