POWER TRANSMISSION SYSTEM

Provided is a power transmission system that can determine an optimal frequency for power transmission, and transmit power efficiently. The power transmission system of the present invention includes: an inverter unit 130 that converts a DC voltage into an AC voltage of a predetermined frequency to output; a power-transmission antenna 140 into which the AC voltage is input from the inverter unit 130; and a power-transmission control unit 150 that controls a frequency of an AC voltage output by the inverter unit 130, with electric energy being transmitted via an electromagnetic field from the power-transmission antenna 140 to a power-reception antenna that faces the power-transmission antenna 140, wherein the power-transmission control unit 150 controls in such a way as to select a frequency at which an antenna unit works as a constant voltage source when seen from a load side, to transmit power.