A switching power supply circuit has a current mode control circuit including current detection means, and current mode signal generation means for generating a current mode signal being a drain current of a first MOS transistor obtained by supplying a first current information signal, which is an output signal of the current detection means, to the gate of the first MOS transistor, and by connecting a first resistance to the source of the first MOS transistor, and supplies the current mode signal to a feedback control system of the switching power supply circuit.