WIRELESS POWER TRANSMISSION DEVICE

A wireless power transmission device comprises a power reception device 2 including a power reception coil 21 which receives the power transmitted from a power transmission device 1, a resonance circuit 22 connected to the power reception coil 21, a load circuit 24 to which a first signal having a first power value is supplied from the resonance circuit 22, a power measuring unit 23 which measures the first power value, and a transceiver 26 which transmits the first power value to the power transmission device 1, and the power transmission device 1 including a power source 11 which generates a second signal having a second power value, a resonance circuit 12 including a plurality of inductors and capacitors to which the second signal is input, a power transmission coil 13 connected to the resonance circuit 12, which transmits the power, a power measuring unit 15 which measures the second power value, a transceiver 17 which receives the first power value from the transceiver 26 , and a control circuit 16 wh.ich calculates power transmission efficiency using the first power value and the second power value and adjusts an inductance value of the inductor and/or a capacitance value of the capacitor based on the power transmission efficiency.