A switching power supply circuit comprises: current detection means for
detecting a current flowing through an inductor; current holding means
for holding the current flowing through the inductor over a past
predetermined period; and current superposition means for adding to an
output of an error amplifier a current superposition signal which makes
an adjustment, based on a present current information signal as an output
signal of the current detection means, such that the ON-period of a
switching signal of a PWM comparator is shortened, and also makes an
adjustment, based on a past current information signal as an output
signal of the current holding means, such that the ON-period of the
switching signal of the PWM comparator is lengthened.