A power transmission device of a non-contact power feeding device according one or more embodiments may include a control circuit configured to control at least one of a switching frequency or a voltage of AC power supplied from a power supply circuit to a transmission coil, on the basis of a change over time in a strength of a magnetic field detected by a magnetic field detection element configured to detect a strength of a magnetic field generated from the transmission coil of the power transmission device. Whereas, a power reception device has a resonant circuit having a reception coil configured to receive electric power from the power transmission device and a resonance suppression coil arranged to be capable of being electromagnetically coupled to the reception coil.