A power transmitting device is configured to perform a “power transmission frequency adjustment control” applied to adjust a power transmission frequency representing a frequency of power to be transmitted. A power receiving device is configured to perform a “resonance frequency adjustment control” applied to adjust a resonance frequency of a power receiving unit contactlessly receiving the power transmitted from the power transmitting device. The power transmitting device uses control information received from the power receiving device to determine whether the power receiving device has a function of performing the resonance frequency adjustment control applied to adjust the resonance frequency of the power receiving unit. When the power receiving device has the function of performing the resonance frequency adjustment control, the power transmitting device selects one of the power transmission frequency adjustment control and the resonance frequency adjustment control that has a higher resolution.