The ferrite plating with applying power ultrasound waves of 19.5 kHz and 600W enabled us to encapsulate entirely MnZn ferrite cores for transformers with Ni$sub$x/Zn$sub$y/Fe$sub$3-x-y/O$_4$coating. Supplying a NH$_4$OH solution during the plating broke the limit of the solubility of Ni ions to ferrite-plated films. The electrical resistivity of the NiZn ferrite coating increased with increasing the Ni and Zn content, reaching 2.3${ imes}$10$^$5/Ωcm at the composition of Ni$sub$0.24/Zn$sub$0.30/Fe$sub$2.46/O$_4$. The saturation magnetization was 540 emu/㎤. As a result, the MnZn ferrite cores were successfully encapsulated with the NiZn ferrite coatings for an insulation layer.