A power transmission system has an AC power source and a high-frequency power driver that make up a high-frequency power source, and a primary self-resonant coil and a secondary self-resonant coil. The secondary self-resonant coil is magnetically coupled, by magnetic field resonance, to the primary self-resonant coil, and receives as a result high-frequency power from the primary self-resonant coil. The coils of the primary self-resonant coil and the secondary self-resonant coil resonate in an even mode when high-frequency power is transmitted from the primary self-resonant coil to the secondary self-resonant coil. Specifically, the primary self-resonant coil and the secondary self-resonant coil resonate in a state where currents in mutually opposite directions flow in the two coils.