A non-contact power transmitting/receiving system calculates a loss Plo as a power difference between a transmitted power Ptr of a power transmission unit of a power transmission device and a received power Pre of a power receiving unit of a power receiving device. The non-contact power transmitting/receiving system sets a smaller value to a target transmitted power Ptr* when the calculated loss Plo is greater than a reference value Ploref, than a value when the calculated loss Plo is equal to or less than the reference value Ploref, and controls a high-frequency power circuit with the set target transmitted power Ptr*.