A switching power supply circuit includes a switching output unit that generates an output voltage from an input voltage using an output transistor, a switching control unit that controls on and off of the output transistor so that the output voltage or a feedback voltage in proportion to the output voltage agrees with a predetermined reference voltage, and one of an interrupt unit and a reference voltage setting unit. The interrupt unit forcibly turns off the output transistor during a period while the output voltage or the feedback voltage is higher than a threshold value voltage that is higher than the reference voltage in response to a periodic load change. The reference voltage setting unit temporarily changes the reference voltage in synchronization with timing of a periodic load change.