A switching power supply device includes: a chopper circuit that adjusts a DC voltage input through a reactor to a desired DC voltage by performing an on/off operation of a switching element; an inverter circuit that converts an output of the chopper circuit into a desired AC voltage; a first capacitor that is provided on a side of the inverter circuit relative to the switching element; a second capacitor that is provided on a side of the inverter circuit relative to the switching element; and a resistor that is in a resonant loop formed by three constituent elements that are the first capacitor, the second capacitor, and a wiring inductance between the chopper circuit and the inverter circuit, where the resistor is connected in series to the second capacitor and inserted between the DC bus-bars.