The efficiency of a wireless power transfer system changes with the load. To solve this problem, an impedance matching method has been developed. Conventional methods control the equivalent load to the optimal value using circuit parameters and the detected load voltage and current. However, they require estimating the mutual inductance M in case of misalignment or an airgap change. M-estimation has some issues such as a limited operating range. In this study, we developed a high-efficiency operation method that can respond to a change in M without its estimation by controlling the currents in the coils to equalize them. We confirmed that the developed method enables highly efficient operation without M-estimation despite misalignment.