Abstract: A power receiving device includes: a power receiving antenna to wirelessly receive AC power from a power transmitting antenna in the power transmitting device; a power receiving circuit to convert the AC power received by the power receiving antenna into DC power and to output the DC power; an impedance adjustment circuit disposed on a transmission path between a load that utilizes the DC power and the power receiving antenna, the impedance adjustment circuit being capable of causing a change in input impedance thereof; and a power reception control circuit to control the impedance adjustment circuit. The power reception control circuit consecutively changes a value of the input impedance of the impedance adjustment circuit to a value selected from among a plurality of values, determines from among the plurality of values a value at which power to be supplied to the load becomes largest, and sets and maintains the input impedance at an operating impedance value that is based on the determined value.