Disclosed are a control circuit and control method for a comparator-controlled type DC-DC converter that can prevent the generation of audible noise due to the difference between relevant switching frequencies and prevent the increase in the input power source ripple voltage. A phase comparator FC outputs a compared-result signal CONT in correspondence with the phase difference between an output signal FP2 and a delay signal FR1. A delay circuit DLY2 performs a feedback control for adjusting the amount of retardation time in correspondence with the compared-result signal CONT. And, the delay circuit DLY2 outputs a delay signal FR2 after the passage of a prescribed amount of retardation time from the time when the falling edge of an output signal SQB2 has been input. At a time t16 that is after the passage of a prescribed amount of time, there is obtained a time delay DT2b that causes the period TT1 of the delay signal FR1 and the period TT2b of the output signal FP2 to coincide with each other and that makes zero the phase difference between the delay signal FR1 and the output signal FP2.