A short-circuit determination device is provided in a switching power supply device. The switching power supply device converts a power supply voltage applied between an upper power supply line and a lower power supply line and outputs the power supply voltage to a load through an intermediate node. The switching power supply device includes a plurality of upper switching elements and a lower switching element. Each of the plurality of upper switching elements has an electrical conduction terminal and a control terminal. The electrical conduction terminals are connected in series between the upper power supply line and the intermediate node. The control terminals are driven at a same level as each other. The lower switching element has an electrical conduction terminal connected between the lower power supply line and the intermediate node. The lower switching element and the plurality of upper switching elements are connected in series.