WIRELESS POWER TRANSMISSION DEVICE

A wireless power transmission system according to the present invention includes: a pair of antennas 107 and 109 , between which power is transmissible wirelessly by resonant magnetic coupling at a frequency f0 , one of which is a series resonant circuit, and the other of which is a parallel resonant circuit; and a control section 100 , which controls a transmission frequency according to the magnitude of the power being transmitted between the antennas 107 and 109 . If the power transmitted between the antennas is greater than a reference value P1 , the control section 100 sets the transmission frequency to be a value that falls within a first level range that is higher than the frequency f0 . But if the power is smaller than the reference value P1 , then the control section 100 sets the transmission frequency to be a value that falls within a second level range that is lower than the first level range.