Provided is an electric power transmission system that can efficiently transmit electric power when a battery 204 is charged in a power receiving-side system. An electric power transmission system 100 of the present invention is characterized by at least comprising: a power transmission antenna 105 that constitutes a series resonator with an inductance component of L 1 and a capacitance component of C 1 , and to which AC power is input; a power receiving antenna 201 that constitutes a series resonator with an inductance component of L 2 and a capacitance component of C 2 , and which receives electromagnetic energy from the power transmission antenna 105 via electromagnetic fields; a rectifying unit that rectifies an output of the power receiving antenna 201 to output DC power; and a load to which an output of the rectifying unit is input, wherein, at times including when a coupling coefficient between the power transmission antenna 105 and the power receiving antenna 201 is k, if load resistance value R is used in a range that satisfies R min ‰¤ R ‰¤ R max , the following relationships are established: [Formula 2] L 1 �¢ C 1 = L 2 �¢ C 2 and [Formula 6] L 1 C 1 > L 2 C 2 and [Formula 8] R min ‰¤ k �¢ L 2 C 2 ‰¤ R max