Power feeding device, power feeding method, and power feeding system

Disclosed herein is a power feeding device including: power transmitting section which transmits electric power by way of a magnetic field; a set of first and second electrodes (14A,14B) which are spaced from each other; a power supply (130) which applies a voltage between the first and second electrodes; and a detector which detects whether foreign matter is present on the power transmitting section or not based on the voltage applied by the power supply.