A power supply circuit includes a switching element and a control section. The control section converts back electromotive force generated at the time of the operation of the switching element to optical energy and converts the optical energy to an electrical signal. Furthermore, the control section drives the switching element on the basis of the electrical signal obtained by converting the optical energy. Accordingly, unlike a case where surge energy is regenerated by resonance, there is no need to use a resonant element such as an inductor. As a result, circuit scale is reduced.