A switching power-supply device includes a switching element; an output circuit; a feedback signal generation circuit; a control circuit that drives the switching element, based on the feedback signal, and controls the voltage of the power-supply output; a correction circuit that corrects a signal level of the feedback signal, wherein the control circuit comprises: an oscillation circuit that generates an on-trigger signal; a current detection circuit that generates a current detection signal; a difference detection circuit that generates a difference detection signal; a comparison circuit that generates an off-trigger signal, based on the current detection signal and the difference detection signal; and a first load detection circuit that controls an operation of the correction circuit, based on the current detection signal, and wherein the control circuit changes a setting voltage of the power-supply output, according to the signal level of the feedback signal.