Power-receiving device and control method for power-receiving device, and computer program

A power-receiving device (200) is provided with: a power-receiving unit (201) for receiving power transmitted from the transmission unit (101) of a transmission device (100), and positioned so as to face the transmission unit with a space interposed therebetween; a converter unit having a first circuit (203) for converting the AC voltage of AC power outputted from the receiving unit into a first voltage which is a DC voltage having the same or different voltage as/than the AC voltage, and a second circuit (204) for converting the AC voltage into a second voltage which is a DC voltage having a different voltage than the AC voltage and being higher than the first voltage; a charging unit for charging using the power outputted from the converter unit; detection units (208, 209, 210) for detecting the impedance of the charging unit; and a selection means (210) for selecting the first circuit or the second circuit on the basis of the detected impedance.