Wireless power transfer via magnetic resonant coupling can be used to supply power to a mobile robot within a few meters of a transmitter coil. However, when the robot moves or its power consumption fluctuates, its input impedance varies and causes power reflection. Therefore, we propose the use of a driver coil on the transmitter side to match the input impedance. The input impedance is matched and power reflection is eliminated by regulating the coupling coefficient between the driver and the transmitter. During experiments, the transmitting efficiency showed good agreement with the calculated value, and the input impedance was matched under varying distances and load resistances. Therefore, the proposed system was demonstrated to solve the power reflection problem in mobile robots.