A push-pull switching power converter includes, between high and low output terminals of a DC power source, a series circuit having a first switching device, a primary winding of a first transformer, a primary winding of a second transformer, and a second switching device in this order, and a series circuit composed of two capacitors, as well as a partial path for current resonance. The partial path connects middle points of the two series circuits. Voltage resonance causes the waveform of a switching voltage, which corresponds to the difference in voltages between high potential terminal of a primary of the first transformer and low potential terminal of a primary of the second transformer, to be a sine wave. Current resonance causes the waveform of a switching current, which corresponds to a combined current of primary winding currents of the first transformer and the second transformer, to be a sine wave.