According to an embodiment, a switching power supply circuit includes a comparison circuit and an operation control circuit. The comparison circuit operates intermittently in response to an operation control signal. The comparison circuit compares a feedback voltage based on the output voltage with a reference voltage to generate a comparison result signal representing a result of comparison. The operation control circuit generates the operation control signal based on the clock signal and the comparison result signal. The operation control circuit generates an operation control signal synchronous with the clock signal, if the comparison result signal is at the first level.