A power supplying device includes a power transmission circuit transmitting AC power and a power transmission resonance circuit including a power transmission coil. A power receiving device includes a power reception resonance circuit including a power reception coil. When a coupling coefficient between the power transmission coil and the power reception coil is a predetermined coupling coefficient, resonance of a first resonance mode having a first resonance frequency and a second resonance mode having a second resonance frequency are generated, a resonance frequency of the power transmission resonance circuit and the power reception resonance circuit is set to a value which is one of the first and second resonance frequencies, and the set value is a frequency deviating from a reference resonance frequency of the power transmission resonance circuit alone by a predetermined deviation frequency or more. A driving frequency of the AC power is set to the set value.