A switching power supply includes: a switching device connected between a power supply input terminal and a ground terminal via an inductance element; an output circuit that generates a prescribed output voltage by rectifying and smoothing current obtained from the inductance element as the switching device is switched ON and OFF; an output voltage control circuit that controls an ON time of the switching device on the basis of a feedback voltage obtained through the output voltage of the output circuit; and a short-circuit detection circuit that outputs a short-circuit detection signal by detecting short-circuits in the switching device on the basis of a voltage applied to a control terminal of the switching device when the switching device is ON, the short-circuit detection signal being used to control operation of the output voltage control circuit so as to gradually reduce the ON time of the switching device.