A switching power supply apparatus includes a first series circuit including a third rectifier device and a fourth rectifier device and that is connected between a positive output terminal and a negative output terminal, and a first capacitor a first end of which is connected to a connection node between the third rectifier device and the fourth rectifier device and a second end of which is connected to an end, not connected to the first series circuit, of a first rectifier device or a second rectifier device. The first series circuit and the first capacitor define a snubber circuit.