<p>A power supply circuit includes a multi-level voltage output circuit and a switching circuit. The multi-level voltage output circuit has an input end to which a voltage having a periodically changing magnitude is inputted and a plurality of output ends from which a plurality of voltages differing in amplitude is outputted. The switching circuit is configured to select one voltage whose instantaneous value belongs to a predetermined range, from the plurality of voltages outputted from the multi-level voltage output circuit, based on a change in a voltage magnitude or a voltage phase at a front end or a rear end of the multi-level voltage output circuit. The switching circuit is configured to supply the selected voltage to a load.</p>
