WIRELESS POWER TRANSMISSION DEVICE

PROBLEM TO BE SOLVED: To provide a wireless power transmission device that allows maintaining a desired power-receiving voltage while reducing variation in frequencies excellent in power transmission efficiency even if the distance between a power-feeding coil and a power-receiving coil is changed.SOLUTION: A wireless power transmission device 100 includes a power-feeding coil L1, a power-supply circuit 120, a power-receiving coil L2, a capacitor C2, and a load circuit RL. The power-supply circuit 120 includes a power-supply VG, a voltage conversion circuit 140, and a current detection circuit 130 detecting a current value of a current flowing through an input side or an output side of the voltage conversion circuit 140. The voltage conversion circuit 140 has a voltage conversion section 150 transforming an input voltage supplied from the power supply VG, and a transformation control section 160 connected to the voltage conversion section 150. The transformation control section 160 controls a voltage value transformed by the voltage conversion section 150 on the basis of the detected current value detected by the current detection circuit 130.