A switching power supply device of a nonlinear control manner is provided, which includes: a reference voltage generation portion, for generating a reference voltage; a ripple injection portion, for using a switch voltage at one end of a switch element to generate a ripple component, and injecting the ripple component into the reference voltage to generate a ripple reference voltage; a comparator, for comparing a feedback voltage corresponding to an output voltage with the ripple reference voltage; a switching control portion, for performing on/off control on the switch element based on an output signal of the comparator; and an offset adjustment portion for generating an offset voltage corresponding to the switch voltage, and setting any of the reference voltage, the feedback voltage, and the ripple reference voltage to the offset voltage.