The invention aims to obtain a beam characteristic in which resolution in an orientation direction is not dependent on depth, and with which there is no discontinuity in the vicinity of the focal point of an echo signal. An ultrasonic testing device 10 is provided with a transmitting and receiving unit 30 and a signal processing unit 40. The transmitting and receiving unit 30 employs a probe 100 to transmit, from a plurality of mutually different positions on the surface of a subject, ultrasound signals having a focal point within a specific zone in the depth direction inside the subject, in such a way that the transmitted ultrasound signals overlap partially in an orientation direction perpendicular to the depth direction, and to acquire echo signals from inside the subject. In the specific zone, the signal processing unit 40 establishes a sound wave propagation model of a planar sound source having a certain beam width at the focal point. For a zone not including the specific zone inthe depth direction the signal processing unit 40 establishes a sound wave propagation model which takes the focal point as a point sound source. The signal processing unit 40 combines the echo signals on the basis of delay times calculated geometrically using the sound wave propagation models, and generates inspection data corresponding to each of the plurality of positions.