The technology concerning improvement of resolution of an acoustic wave sensor having a hemispherical shape or the like is provided. An ultrasonic transducer unit includes an ultrasonic transducer having a plurality of ultrasonic transducer elements, and a probe casing configured to support a plurality of the ultrasonic transducers, and to have a concave portion facing a subject. The plurality of ultrasonic transducer elements is arranged on a same plane facing a center of curvature of the probe casing. The plurality of ultrasonic transducer elements is arranged in a rotationally symmetrical manner about a normal line connecting the center of curvature of the probe casing to a point on a plane of the ultrasonic transducer.
