Electrical impedance distribution reconstruction was examined based on ultrasonic B-mode imaging with a three-layered breast model by a multisensing probe. In the probe, 16 electrodes arrayed on a thin film are pasted on the surface of the ultrasonic probe. The electrical voltages are measured by several combinations of the 16 electrodes. In addition, an ultrasonic B-mode image is simultaneously obtained using the probe. The electrical impedance distribution is reconstructed by using the B-mode image as the prior information. Therefore, the probe makes both the electrical conductivity and ultrasonic B-mode images possible. In the experiment, a three-layered breast model and multisensing system were developed, and the conductivity distribution and B-mode images of the model were obtained. The results indicate that estimation of the tumor position in the breast model is possible using the developed system, even though there are some problems, such as the stability of the model and the measurement accuracy of the system.