A possibility of using a standard beam tomography procedure to reconstruct the two-dimensional distribution of the nonlinear parameter of a medium in ultrasonic systems with wave phase conjugation (WPC) is investigated. The mathematical model constructed for the confocal geometry of the ultrasonic WPC system is confirmed by experimental results. The image of a nonlinear object is built on higher harmonics of the phase-conjugate wave. The results demonstrate an increase in the contrast of the image obtained for the distribution of the nonlinear parameter in the case of using the second harmonic of the phase-conjugate wave (the fourth in relation to the incident wave).