Power-transfer system

This power-transfer system (A) is provided with a power-transmission device (10) that transmits AC power and a power-reception device (20) that receives AC power. The power-transmission device (10) is provided with AC converters (11a, 11b), a power-transmission-side resonance coil (12), and a power-transmission-side control device (11c). The power-reception device (20) is provided with a power-reception-side resonance coil (20), a rectifier (22), a DC converter (23a), a power-reception-side control device (23d), and a power-supply circuit (23c). After starting up due to the input of a controlling power-supply voltage, the power-reception-side control device (23d) transmits, to the power-transmission-side control device (11c), a measurement result obtained by measuring the output voltage of the rectifier (22). From when the transfer of AC power is started until the aforementioned measurement result is received, the power-transmission-side control device (11c) controls the AC converters (11a, 11b) so as to gradually increase the output voltage of the rectifier (22), and after the aforementioned measurement result is received, the power-transmission-side control device (11c) controls the AC converters (11a, 11b) on the basis of said measurement result so as to bring the output voltage of the rectifier (22) to a value that is appropriate as an input voltage to the DC converter (23a).