An object of the present invention is to achieve the reduction of EMI, the improvement of conversion efficiency, and simplification of the input filter. Provided is a switching power supply device that comprises: a chopper circuit that turns on/off the passage of a current to an inductor by means of a switching element; and a switching control circuit that switches the switching element so that an input voltage and an input current have the same phase and a similar shape. The switching control circuit is configured to switch the switching element at a switching frequency that is proportional to an input voltage dependent term of a formula that expresses a third harmonic component of ripples of the current flowing to the inductor.